So I would work the variations that you have rather than just varying the volume on the three sessions because I would get bored to tears just benching the same weight for that long. That's just me and my ADD though
Have you ever tried speed benching? What about ballistic benching? Ballistic is where you do your speed reps as per usual but turn the bar around BEFORE it hits your chest. My shoulder has been too beat up to do this for a while but had some success with it before Christmas. Helps me stop sinking the bar into my chest and improving the stretch reflex.