I used to asked this question when I was younger as well. It wasn't until I got older that I realized that the question I should have been asking was "what training brought about your best size/strength gains?" or "how did you train to get from an intermediate level to advanced?"
In other words, you don't ask the 275 pound ripped guy with a 700 squat and 500 bench how he is training right now. Ask him how he trained to get there. If he tells you he was squatting 500 when he was 14 or benching 400 3 months after he started lifting, he probably won't have a lot to offer you in the way of meaningful advice if you are a guy that struggles in those areas.
Sometimes the answer is that he's training the same way. Sometimes it's quite different. But what I have found to be most common is that (drum roll) these guys ate like crazy, and just concentrated on getting as strong as possible on the big lifts.
For example, the training routines I supply in my manuals are the ones I found I made the biggest strides with as a pretty advanced guy. Of course they were combined with a heavy food intake, but the splits and routines were no frills and no BS.
Going into this mass phase I am going to give a different split a run and see how it works out. Mainly because I have neglected a few phases of my training, and to shake things up a bit. But I couldn't completely recommend this to anyone/everyone because not everyone has the same problems or needs I have at the moment in terms of training. This is a lot like the guy I wrote about that can care about big arms because his base is big enough. I do need to get bigger in order to increase my strength ceiling, but I'm at the stage where that means 5-7 pounds of lean mass, which equates about to about a 14-18 pound weight gain total (in a perfect world). And even for that, I am going to have to train my balls off, sleep good every single night, avoid distractions, and be as focused as I've been in some time. And even then, I could still fall short. But I won't fall short because of effort.
But for intermediate guys or guys that have been stuck for a while, what I really recommend is to ask advanced guys what they did to get to where they are at. Not what they are doing now. This is one reason why in the manuals, I wrote about the most productive training methodologies I used to get me where I am now. Not what I am doing at this moment (although the truth is, there really isn't much difference overall as my philosophy hasn't changed).
For example, a lot of guys search high and low for a certain bodybuilders or powerlifters routine. This really isn't going to tell you a lot, even if you take anabolics into account (which is a completely different subject). But if a guy has gone through 7 or 8 different evolutions of what he needs to get to another level, it might be completely useless to you.
In the past year, I know guys that have gone from training 4-5 days a week, to two days a week. I know guys that have gone from 4 days a week, to 2 days a week, then to 3 days a week.
I've known guys that went from high volume to HIT, and from HIT to high volume.
It can be difficult to track down. However what I have generally found is that when guys get to a new level, more times than not, they rode one horse for a long time and rode it to death, and were consistent in every aspect. There's that word again. Consistency.
But if you were to think about a training timeline on a 1-10 scale with each number representing a change in methodologies or philosophies that lasted for a long while, it could look like this...
Obviously as a rank beginner, guys can be all over the place for a while (1-5). Then as they learn a few things, get bigger and stronger they figure a few things out that work for them, and grind on them for a while (6-7).
Soon frustration sets in and often times the advanced guy hops around again (7,8,9), looking for that holy grail that will take him to that next and final level. Eventually he settles on something (usually the basics again), and rides it out again until he gets there (9-10), knowing that jumping around all over the place is never going to work. A lesson that doesn't always take the first time around.
And this is why I say to avoid asking the question of what the advanced guy is doing right now. Often times, he's in that 7-8-9 category searching for answers, just like you are. If you can find someone who has reached a really high level of strength or development that has a lot of years in, what you will most often find is that to get there, he settled on some training habits and rode those for a long time again. You'll also most likely find that if he wasn't a naturally big or strong guy and had to work for it, that he had another time where he made huge gains as he settled into a few habits as well.
Slow and steady wins the race.