A timed offset can be used to open and then close retract doors. The speed can be set as well...both "in" and "out" speeds. The offset mix is set to activate upon activating the retract gear. The doors open, stay open for a period of time, and then close. The mix would then be "off". You'd use two timed offset mixes in this case. One turns on when the gear switch is set to retract and one turns on when the gear switch is set to extend. The timing would be slightly different for the two modes, and each offset mix turns itself off when the 'off' time has elapsed.

You could use a cascading offset to operate things that need to go in sequence from a single servo. For an extreme example, let's say you had a realistic ejection seat in a model jet. The first part of the servo movement could open the canopy release and further movement of the servo would activate the ejection spring. Yes, that's a fanciful example, but you could do the same with bombs. Use four movements of the servo to drop a series of bombs. In a bomb bay, the bombs need to drop in a sequence, so you could have up to four sets of bombs drop. The servo would move to four different positions, and each succeeding position would drop the next set.

....or even have one servo open the doors, and then have further movement drop the bombs after a bit of time.

Have a Naval destroyer eject a series of depth charges or launch a series of torpedoes....your imagination is the only limit.