I generally want the eye caps off as soon as possible to get them eating sooner than later, but sometimes when they are on for a long time even a soak won't get them off easily.
To get off stubborn stuck eye caps I soak for a longer period of time.
30 minutes in a small locking lid tub with 1 to 1 1/2 inches of 85 to 88 degree water.
Replenish the water with more warm water and go again for 30 minutes.
Most stuck caps will come off after an hour of soaking in 100% humidity