There is a rep range for a specific goal you are trying for.
When you are using close to maximum weight (90%+) and working the 1-3 range, you are building strength and regardless of how many sets, your muscle mass increase will be minimal.
Legs tend to have more slo-twitch muscles fibres because that are more "endurance oriented' than arms of chest, etc.
Because of that, they TEND to need a higher rep scheme to cause muscle growth for mass (hypertrophy).
Typically recommended are the 10+ range ( 10-12 being more popular) BUt you do tend to sacrifice some strength in that.
So many who want the "best of both" work in the 8-10 rep range ( or the 6-8 if they prefer to focus on strength but also want some mass).
All these is relative in the sense that you can only get bigger by getting bigger ( eating more to put on mass).
Genetics will dictate how much you can put on and what shape your legs will be and, through trial and error, which rep range is best for you.
I think that an ideal method is to focus on strength and get to a good number and then focus on mass.
SO you would, for example, do the 3-5 range till you get to 2X your BW for 3 reps and then take a week off and focus on mass building in which you would work the 8-10 rep range.
As for set, I have to be honest here:
I have worked on different protocol and found that ALL of them work to an extent.
BUT, if you do more sets you will get better at doing squats ( indispensable for power lifting and olympic lifts).
I have worked the various HIT protocol out there and say this:
Unless you really CAN go to failure, you should stick to something else.
If you can go, there are very few protocols that works as well (IMO).
Psalms 144:1
Praise be my Lord my Rock,
He trains my hands for war, my fingers for battle !