We focus too much on the "latest" study. Tomorrow there will be another research that will disprove this research.
If by "we" you are referring to me and my mention of the more recent literature then I reject your criticism. Scientific understanding evolves and there is much to be learned by staying abreast of the recent literature. A reasonable person, thinking critically, can leverage that information to improve what is already well understood.
We've all seen what it takes to gain muscle based on real observational evidence. Those that are successful, lift consistently, with intensity, and eat correctly. What we can gain from the research is insight about how to optimise what is already common knowledge.
What happened to going to the gym, give it your all, eat right, and recover well. No offense to anyone as I see this everywhere... "tHe LatEst stUDY shOws tHis meThod iS SupeRIOr".
The latest study is not prescriptive. Anyone that looks to research to develop a program is doing it wrong. A skilled coach will consider the athlete and their individual characteristics to create a program that works for them. Generally speaking, the latest research suggests that "more is better". I wouldn't hesitate to have a noob lifter in his 20s squat 3x a week. I'd hesitate to suggests something similar to a noob lifter in his 40s, nor would I recommend that to anyone of an advanced training age that wasn't a gifted athlete squatting north of 4 plates.
There is no research that tells me that these are good decisions. If they are good decisions, they're only the product of experience and observation.
The research can give us clues, though. For example, time under tension makes no difference. Maybe someone believes that taking a very long time to complete reps will improve gains. Turns out that it doesn't. Getting close to failure does, which may inform my choice of exercise in that I'm going to push a chest press machine closer to failure than I will a barbell bench.
The recent research can help us optimize for particular conditions. If we want to bring up a particular muscle group, we know that up to 30 sets per week or so will increase hypertrophy and we could reduce the sets per week for other muscle groups down to near minimal effective dose and focus all the recovery bandwidth on that particular muscle group.
If we want to maximize growth across all body parts, it helps to understand the diminishing returns that occur from doing more sets in a given workout and more sets in a given week. More is more, but not linearly. In a given workout 3 sets for a particular muscle group yields 1.5x the growth as 1 set and it continues to diminish from there.