I would think that as long as you have a setup that encourages you to progressively overload and continue gaining strength you would be in good shape no? Now how you go about that would then come down to your comfort level and what you find to be most effective.
For example if you find you do well on the 5/3/1 vs the 5x5 then do the 5/3/1 you are still promoting growth.
When it comes to overall intensity, I believe intensity (in physical workout not your mental intensity) is basically a triangle of Rest, weight and reps.. That sounds right, so if your wanting to increase your intensity, you can shorten your rest, or increase the weight, or increase your reps. or some combination that makes it harder than before, so then I would say that at heavier weights, (so now we are at the advanced powerlifter not a novice/intermediate like myself for example) what is the best scheme to increase our intensity, in a safe effective protocol to progressively overload.
I think at that point it becomes a personal decision as the program I am running now (mine is slightly modified) but it was used a professional powerlifter and he would be doing 3 sets of 8 of 2 compounds a day AFTER doing a strength session. (20% heavier or so) for some people that my be too much just like a 5x5, and they find they respond better to something like a 5/3/1.
Basically this whole rant is me saying that you at some point are going to have to listen to your body on this, but the essentials remain the same.
always progressively overload
Thats my ramble
Philippians 1:21: For to me to live is Christ, and to die is gain.