I remember when I would chicken out of taking the bar all the way down on bench for fear of not getting it back up. One day I realised that the only two places I need worry about are my sticking point about four inches up and the odd failure to lock out when my triceps let me down. This basically meant that once I'd brought the bar down I might as well bring it all the way down since if it was going to fail it was already too late. I can't recall ever failing right on my chest and there's no good reason besides fear for someone not to do the full rep on bench press unless they're deliberately doing partials.