Having been locked in chastity recently I found myself thinking is this fun or cruel? My thoughts are that if there’s some fun at the end of it then its basically extended foreplay, but that needs the keyholder to provide the tease, and to mess with the locked one’s mind. Otherwise with no attention, no goal or reward at the end, its solitary confinement and whilst it’ll still set off power emotions in the mind, its mostly punishment.
I do know that once that device is locked on me I act differently. Apart from feeling controlled there’s the drive to please your keyholder and hope that the efforts you’ve made will be rewarded.