Yeah, absolutely. 5x5 is a good compromise between relative intensity and muscular fatigue.
As for single max sets vs. multiple sets, remember, you can't just do maximal effort all the time if you only want strength. Even if it would work for any kind of countinued progress (which it wouldn't) doing intensties over 90% all the time will quickly burn you out and overwhelm you. It's not just the difference between hypertrophy training and strength training although people still insist on thinking of it that way.
It is not just your goals that determine whether you might do single max sets sometimes, or multiple sets of low reps, or moderate sets of high reps --- it's just plain old hard reality.
But if this goes any further I think we all know where it will head
