Some phals just like to bloom. You will hear stories of how some phals can bloom for a couple years with nice size flowers and at times adding other spikes as well. It really depends on the plant. Most phals like a rest. For those, if you don't cut the spike they will continue blooming, but you will get few flowers and they will often be much smaller. I don't usually cut spikes, and if the plant is ready to rest the spikes will dry out on their own. I have some that will let the spike stay green until the next blooming and bloom off the old spike as well as a new spike. It just depends on the plant and whether you prefer to cut the spike. I usually leave it up to the plant. I do cut spikes on plants growing new roots or when they are infested with bugs. Also; when the flowers are too small or obviously a drain on the plant i'll cut the spike even if it still has good flowers.