You wont advance very much in trials if u don't push yourself. At least that's how I understand it.
I ride every day for a couple of hours and fall off at least 2 or 3 times on even the smallest of obstacles so all I would say is plan ahead and if u don't think you're up to something on one day, don't do it. Leave it until you're in the right frame of mind.
That way u minimise making stupid mistakes i.e. not spotting a sharp rock on the floor which could burst your tyre and cause you to fall off.
Weigh up the risks