It's used more often than you'd think:
Castle of Doctor Brain, Component.sc(258): hold: 1
Conquests of the Longbow, fMonk.sc(625): (gSFX number: 15 loop: -1 play: hold: 1)
Conquests of the Longbow, jment.sc(83): hold: 1
Conquests of the Longbow, jwitchct.sc(430): (gRgnMusic2 number: 506 loop: 1 play: hold: 1)
Conquests of the Longbow, ZScript.sc(413): hold: 10
EcoQuest 1 CD, RM600.sc(105): (gLongSong number: 665 loop: -1 play: hold: 10)
EcoQuest 2, ceremony.sc(498): (gGameSound1 number: 427 play: hold: 1)
EcoQuest 2, ceremony.sc(535): (gGameSound1 hold: 2)
EcoQuest 2, ceremony.sc(546): (gGameSound1 hold: 3)
EcoQuest 2, ceremony.sc(557): (gGameSound1 hold: 4)
EcoQuest 2, ceremony.sc(797): (gGameSound1 number: 434 loop: 1 client: 0 play: hold: 1)
EcoQuest 2, rm640.sc(359): (gGameSound1 hold: 2)
EcoQuest 2, rm640.sc(369): (gGameSound1 hold: 3)
EcoQuest 2, rm640.sc(379): (gGameSound1 hold: 4)
EcoQuest 2, rm640.sc(412): (gGameSound1 number: 636 play: hold: 1)
EcoQuest 2, rm880.sc(557): (gGameSound1 number: 882 loop: -1 play: hold: 1)
EcoQuest 2, rm880.sc(774): (gGameSound1 number: 886 loop: -1 play: hold: 1)
King's Quest 6, rm210.sc(1276): (if (proc913_0 10) (gGlobalSound4 hold: 10))
King's Quest 6, rm580.sc(152): hold: 10 ; twice in this script.
King's Quest 6, rm580.sc(434): (gGlobalSound hold: 20)
King's Quest 6, rm580.sc(601): (gGlobalSound hold: 30)
King's Quest 6, rm580.sc(663): (gGlobalSound hold: 30)
Leisure Suit Larry 1, rm190.sc(126): (sfxBlender play: hold: 10)
Leisure Suit Larry 1, rm505.sc(136): (sfxDialTone play: hold: 10) ; Nine times in this one script.
Leisure Suit Larry 1, rm610.sc(462): hold: 10
Leisure Suit Larry 1, rm610.sc(479): (gLongSong2 hold: 20)
Leisure Suit Larry 5, PushButton.sc(80): hold: 10
Leisure Suit Larry 5, rm250.sc(651): (theMusic3 number: 255 loop: 1 play: self hold: 10)
Leisure Suit Larry 5, rm310.sc(648): (gLongSong number: 311 loop: 1 play: hold: 10)
Leisure Suit Larry 5, rm700.sc(365): (soundFX number: 255 play: hold: 10)
Leisure Suit Larry 5, rm700.sc(374): (soundFX hold: -1)
Leisure Suit Larry 5, rm850.sc(491): (gLongSong2 number: 853 play: hold: 10)
Leisure Suit Larry 6, cObj_620.sc(160): (bedFx number: 621 loop: -1 play: hold: 1) ; twice in this script.
Leisure Suit Larry 6, rm130.sc(147): (limoSFX play: 0 hold: 1 fade: 127 15 21 0)
Leisure Suit Larry 6, rm130.sc(237): (limoSFX hold: 3)
Leisure Suit Larry 6, rm130.sc(546): (if (== (wheel1 moveSpeed?) 0) (limoSFX hold: 2))
Leisure Suit Larry 6, rm380.sc(614): (sfxMachine play: hold: 1)
Leisure Suit Larry 6, rm380.sc(648): (sfxMachine hold: (+ local1 1))
Leisure Suit Larry 6, rm510.sc(204): hold: 1
Leisure Suit Larry 6, rm800.sc(539): hold: 1
Leisure Suit Larry 6, rm800.sc(565): (gGlobalSound1 hold: 2)
Leisure Suit Larry 6, rm800.sc(574): (gGlobalSound1 hold: 3)
Leisure Suit Larry 6, rm800.sc(578): (gGlobalSound1 hold: 4)
Leisure Suit Larry 6, rm800.sc(591): (gGlobalSound1 hold: 5)
Pepper's Adventures in Time, Main.sc(645): (if holdVal (self hold: holdVal))
Pepper's Adventures in Time, rm381.sc(58): (gLongSong number: 110 hold: 1 setLoop: -1 play:)
Police Quest 3, rm057.sc(249): (sFX hold: 1 play:)
Police Quest 4, rm240.sc(47): (gGlobalSound0 number: 505 setLoop: 1 play: hold: 1)
Police Quest 4, rm290.sc(222): (gGlobalSound0 hold: 2 client: self)
Police Quest 4, rm290.sc(226): (gGlobalSound0 number: 507 play: hold: 1)
Police Quest 4, rm290.sc(43): (gGlobalSound0 number: 505 setLoop: 1 play: hold: 1)
Police Quest 4, rm505.sc(249): (gGlobalSound0 number: 505 setLoop: 1 play: hold: 1)
Police Quest 4, rm505.sc(255): (gGlobalSound0 number: 507 play: hold: 1)
Quest for Glory 3, Glory.sc(2300): (if holdVal (self hold: holdVal))
Quest for Glory 3, Head.sc(33): (gOwner hold: 1 3 110)
Quest for Glory 3, openCart.sc(172): (gLongSong number: 100 play: 127 self hold: 1)
Quest for Glory 3, openCart.sc(187): (gLongSong hold: 2)
Quest for Glory 3, openCart.sc(267): (gLongSong hold: 3)
Quest for Glory 3, openCart.sc(277): (7 (gLongSong hold: 4))
Quest for Glory 3, openCart.sc(370): (gLongSong hold: 3)
Quest for Glory 3, openCart.sc(481): (gLongSong hold: 4)
Quest for Glory 3, openCart.sc(541): (gLongSong hold: 3)
Quest for Glory 3, openCart.sc(679): (gLongSong hold: 4)
Quest for Glory 3, rm270.sc(104): (gLongSong fade: 70 5 3 0 hold: 1) ; four times in this one script.
Quest for Glory 3, rm270.sc(337): (gLongSong number: 280 setLoop: -1 play: 1 hold: 1)
Quest for Glory 3, rm270.sc(348): (gLongSong number: 290 setLoop: -1 play: 1 hold: 1)
Quest for Glory 3, rm270.sc(359): (gLongSong number: 300 setLoop: -1 play: 1 hold: 1)
Space Quest 1, rm1.sc(268): (gLongSong2 number: 4 loop: 1 play: 40 hold: 1) ; twice in this script.
Space Quest 1, rm1.sc(296): (gLongSong2 number: 4 loop: 1 play: 80 hold: 1) ; twice in this script.
Space Quest 1, rm1.sc(323): (gLongSong2 number: 4 loop: 1 play: hold: 1) ; twice in this script.
Space Quest 1, rm13.sc(264): (gLongSong2 number: 328 loop: 1 flags: 1 play: hold: 1)
Space Quest 1, rm13.sc(328): (gLongSong2 number: 327 loop: 1 play: hold: 1)
Space Quest 1, rm13.sc(337): (gLongSong2 number: 327 loop: 1 flags: 1 play: hold: 1)
Space Quest 1, rm14.sc(219): (gSoundEffects number: 334 loop: -1 play: hold: 1)
Space Quest 1, rm35.sc(1314): (hoverSound number: 462 loop: 1 play: hold: 1)
Space Quest 1, rm40.sc(280): (gSoundEffects number: 609 loop: 1 play: hold: 1)
Space Quest 1, rm41.sc(490): (gLongSong2 number: 439 loop: -1 play: hold: 1) ; twice in this script.
Space Quest 1, rm44.sc(584): (gLongSong2 number: 628 loop: 1 flags: 1 play: hold: 1)
Space Quest 1, rm45.sc(710): (gSoundEffects number: 610 loop: 1 play: hold: 1)
Space Quest 1, rm50.sc(119): (gSoundEffects number: 502 loop: 1 play: hold: 1 fade:)
Space Quest 1, rm51.sc(754): (gLongSong2 number: 504 loop: 1 play: hold: 1)
Space Quest 1, rm53.sc(380): (gLongSong2 number: 504 loop: 1 play: self hold: 1)
Space Quest 1, rm54.sc(795): (gSoundEffects number: 515 loop: 1 play: hold: 1)
Space Quest 1, rm64.sc(236): hold: 1
Space Quest 1, rm64.sc(392): (emitterSound loop: -1 play: hold: 1)
Space Quest 1, rm64.sc(764): (gLongSong number: 516 loop: 0 play: hold: 1)
Space Quest 1, rm7.sc(46): hold: 1
Space Quest 1, Rock.sc(449): (motorSound play: hold: 1)
Space Quest 1, Sarien.sc(285): (if (== temp0 360) (gLongSong hold: 1))
Space Quest 4, rm072.sc(468): (if (HandsOn 0) (gLongSong2 hold: 1))
Space Quest 4, rm119.sc(21): (gLongSong2 hold: 2)
Space Quest 4, rm120.sc(23): (gLongSong2 hold: 3)
Space Quest 4, rm329.sc(58): (gLongSong2 number: 128 vol: 127 hold: 1 play:)
Space Quest 4, rm330.sc(89): (gLongSong playBed: hold: 1)
Space Quest 4, rm335.sc(197): (gLongSong hold: 2)
Space Quest 4, rm340.sc(48): (gLongSong hold: 3)
Space Quest 4, rm381.sc(1058): (aSound number: 830 loop: 0 play: prevSignal: 0 hold: 1)