You guys are throwing the word “validy” around with completely incorrect definitions, but thats beside the point.
There are two ways to do 5x5 (or any rep scheme for that matter). Actually three ways.
1)You can do all your warmup sets, and then hit 5x5 with the SAME weight for all sets. When you are able to get 5x5 on all sets you increase the weight and repeat.
2)You can ramp up in weight over the course of 5 sets, hitting a 5RM on the final set
3)You can warm up to a weight close to your 5rm and then increase the weight a small amount each set for 5 sets.
Numbers 1,3 are good for size, conditioning gains, while 2 is better for strength. Im not doing 5x5, but somethign similar and was doing option 2. It was great for getting stronger and hitting PR’s but the volume ith “working weights” wasnt enough so ive switched it up. I now alternate, sometimes ramping to a PR and othertimes trying to get as many sets/reps with a weight close to that PR.
So for example. Say im doing DB bench.
Option 2 would have me do something like this. Warmup a bit, 70’s, 80’s, 90’s, 95’s, 100’s. I might get 5 on the last set, or maybe more like 4 or 3. Also, sometimes I dont use the full amount of reps on the sets ramping up to the final set. It might be 70x5, 80x3, 90x1, 95x1, 100x1, then 100x5. It depends on what you are trying to accomplish and how well you can judge your strength. But typically I see now value in doing reps with less than 90% or so of your RM. So if you can do 100’sx5 what good is it to do 80’s x 5.
Then on other days, i’ll warm up, and then do something like this. 90’s x 6, 95’s x 5, 100’s x 5, 100’s x 4, 100’s x 3. These are just hypothetical values, but basically I set a rep range, like 4-6, and if I get 6 I increase the weight, and if not I keep the weight the same.
I think this gives you the best of both worlds, because you can have some days where you focus on hitting a PR for strength, and some days, where you just get your volume in.