Good points 5kg.
Also in addition to the comment about muscling up the weight. I think you'll find the top guys tend not to do that because their strongest groove is the one they have trained. Believe me, if they thought they'd get an extra 10kg from breaking form, then that would be their form regularly!
So if you're still at the point where you need to break form to make a lift then you have some technique and form drilling to do yet. If that is the case you want to avoid doing maximal lifts for a while and get some volume in and really drill the movement path.
You want to aim towards a point where you are lifting in the absolutely strongest range for you. You do that by drilling over and over the form you want to lift in.