We always take the boat out for a spin after rebuilding it (we have a breakdown trailer) at a regatta site. That way we notice anything odd or non-functional.
In my experience the best way to avoid mishaps is to do everything in the same sequence everytime. We dont have a checklist, but when rebuilding we both keep strictly to our respective tasks. Not a problem when one-up, but distraction from competitors or friends can be a source for goof ups. It is very easy to forget to secure a shacle or locksplint with tape when your friends keep pushing beer into your hand.

"50% of winning is 90% preparation." is more than true, even if you disregard training. Last year during the scandinavians we scored no less than two DNF's and a DNC due to lines and other expendables breaking. We knew everything that broke was suspect, but was to cheap and negligent to replace it. Last race the cover on both mainsheet and traveller line broke so we could not cleat them. Finishing the race was hard work..
We learnt the lesson tough, replace anything suspect..