What are your goals? Are you specializing in any lifts? If so, variation is not a good idea. If you are into just general physical preparedness, well then, variation is key. Variation allows you to adapt to various stimulii. I don't even think variation would hurt even if you were specializing in bodybuilding, as long as you kept your core exercises in the same vein' i.e. Chest, Incline DB's one day, BB flat BP the next session Now, if you are into PL or OL, then variation with the assistance moves is a good thing, depending on what you need, but you would still have to focus on the major lifs. Personally, I'm 57 these days, don't focus on OL more than once a year, so the bulk of my training is varied and based on GPP. I don't think I';ve done the same workout per se in any given session more than once. If your goals are similar to mine, then fine, no reason for no variation. if you are tying to excel in a specific lift/exercise, then focus on it.