I try to make mine as near to perfect as I can. I block sand the cork to get any undulations out of it, and then I lay the track as if I were OCD over it (It takes me about an hour to lay a 3 foot piece of flex track). Before scenery, I operate the layout for a year to be sure that there are no flaws, and I correct even the tiniest hiccups.
It seems to pay off - no derailments since 2001.
For what it’s worth, I’m a big fan of Micro-Engineering code 70 track.