Plastic Heads: do you un-tune it when finish?

Guys, I have started using plastic heads from Remo and Evans. I'm from the old real skyn school that youhave to tune it down after finishing the jig. Is this is neccesary with the plastics'? Some people leave it tuned, but I have seen some bongos, including my Timba believe it or not, that loose the roundness on the drums when leave it tuned. What are your thoughts, please?
Thanks!
Thanks!
