We usually go right up until the bitter end, week 6 affectionately known as Crunch Week. We’re attempting to have a competition ready robot done by the end of Week 5 so we’ll have some quality practice time with our drivers but you know how that goes.
What is this “end” you speak of? 
Seriously, there is never a finishing point for your robot. We may bag a robot up, but we have our practice bot and we are going to keep on practicing and iterating to make our bot the most efficient we can. This is what engineers do. We won’t sit around until our competition, we will re-design, iterate, and practice up until our first match. We will repeat this process between all events too, up until our off season events.