Your question is a bit strange since, in the reverb example, you want it to do the effect (reverberation) rather than stop at the same time.
But I understand that sometimes it can do nice effects stopping them.
Once, it was asked a feature to enable/disable "bypass" from the pattern editor. I never added it because a HARD switching causes clicks most of the time and this is undesiderable.
So the option you have is the one that Pikari has said. It can cause clicks also, since there isn't a microrramped change, but it was usefull for more things.
I don't know how this will be achieved in Psycle 2 yet. ( I'm not coding the core)
<[JAZ]> Pa pi pa pa pa pi pa.... ;ĚD