Here is my opinon ;o
First we must identify what's the cause of size increase. It's bigger muscles
the cause of strenght increase is for a large part a more efficient Central Nervous System and bigger muscles. bigger muscles will make your potential of strenght bigger but not directly increase your strenght or just a little bit.
When you work your muscle to make them bigger you use their strenght.
Ok then what's the limiting factor ? It's strenght ! Because no more strenght => you can't work your muscles anymore ! And strenght is CNS !
=> CNS is the limiting factor.
IF I bench press 10x300 to failure I reached my limit of strenght. But what about my pectorals ? Are they still ready to lift weight ? YEP !!! They are not exhausted they are not deads.
But with this HEAVY set you stressed a lot of your CNS... it's not the way to train your muscles but your CNS.
Now how to train ?!
For Strenght you must use all your CNS capacity in a set = Training to FAILURE you can do more sets to failure if you use the same weight. I don't know if doing 2 sets to failure with the same weight will be better than 1... I would say no !!! Training to failure represent the MAXIMUM that you can do on a specific lift, the maximum that your CNS can do. Then next time you train you'll put more weight on the bar because your CNS is more efficient. Low reps will put more stress on your CNS. But if you train with 3-5 reps you'll be stronger in this range ! If you train with 6-10 you'll be stronger in this range !
For Size (I mean maximum size gains because strenght training will make your muscles bigger too but slower) you must use your CNS capacity to work your muscle as much as they can/need. Muscles don't know how much you lift they just can flex and involve fibers (= muscular's cells). You must work your muscles to their limit (can't flex anymore). Then they will be bigger. Because musclar's cells are about being big or small NOT weak or strong !
To favour muscle's work and not your CNS I would do like that :
1) avoid failure or failure but with high reps 10-15. (it should save your CNS to a certain degree). Stop a set when you cannot concentrate anymore on your muscle and begin to concentrate on your barbbel/dumbells.
2) work LIGHT but good form and breathing, FEEL your muscles. Be concentrate on your muscles not on barbbel.
3) quiet slow cadence (2-3 positive 3-4 negative) this should prevent too heavy load and allow you to focus on muscles and help you for concentration and contraction.
4) train frequently (each muscles 2-3x per week) because muscles can recover very fast perhaps they don't need to "recover" but your CNS need a lot of time. So try to avoid failure, train light with high reps.
5) train to maximal pump, burns. You should not be able to flex your arms because of pump That's impossible but that's your goal
6) rest time between sets should be very low (10 to 30 seconds) because your goal is to work your muscle until their limit (can't flex). If you wait 3 minutes between sets you will be able to lift more weight but your muscle will recuperate. so it'll be something like work pause work pause work pause. your muscles pass from 100% of their capacity to 50 then 90 to 40 then 80 to 30 etc... it's not the best way. I think the best way is 100 to 0 with realy little rest time.
example : Barbbel Curl 1 set until it becomes too hard to focus on muscles. rest 10 sec One set lighter. rest 10-20 sec Dumbbels on incline becnh 1 set. rest 10 sec 1 set lighter. 10-20 go to spider curl 1 set 1 set lighter. If your biceps are not pumped to iron and can flex easily after that just do another cycle WITHOUT REST or continue with others exercices.
7) use isolations movements because compouds don't allow you to work a specific muscle ! Compound are strenght exercices. Isolations size exercices. Use many exercices insteed of 1 because muscles should work from different angles for maximal gains. I cannot developp but many studies show us that.... Fro example : Lateral Raises are not enough for TRAPS + SHOULDERS
8) High reps 10-15 (or even more) Because it'll save your CNS and allow a longer time under tension fo your muscles. Longer TUT should be better but then you'll work with so light weight that they won't allow a full contraction of muscles. it's why you need to rest 10-20 sec between sets to be able to take a weight heavy enough to allow full contraction and enough tension on muscles. When muscles are tired, relatively "light weights" are enough for stimulation and tension and full contraction. Don't forget that muscles don't know how much your lift. Depending on their "health" (first set or 10th) it'll be hard or easy for them to lift 10x100.
Ok that's all ;O what do you think ?!
I'll just summary the 2 more important point in my opinion :
1) don't work your CNS (see above)
2) work your muscles to their limit in a minimum of time. => Densitiy. 1 set 2 min rest 1 set 2 min rest will never allow you to work your muscles until their limit. You'll just lift hevier because of partial recovery. Lifting heavy/heaviest is not required. Reduce rest time to the minimum to get a quasi continue TUT until your muscles get tetanized or nearly !
=> this kind of training is SUPER HARD ! Don't think that lifting relatively light is easy. Because if you lift light it's because your muscles's are near to their limit. it's mainly not because your CNS. Because of the "NATURE" of your training, size training (see above).
My god I'm creazy :o But I love it '_';,