I'm not comfortable with that conclusion.
To make progress, you need to stimulate muscles deeply. One set typically cannot recruit all fibers in the muscle. That's why you do more sets, to fatigue some of them, then recruit the rest in subsequent sets.
To gain strength, you need to lift around 70% ... 90% of your 1RM (one-rep-max - the maximum load that allows the complete execution of exactly one repetition). On the lower end of that spectrum, that means 8 rep sets. On the higher end, that means 3 rep sets.
I'd be fine with doing one set of 8 reps at 70% 1RM. But it just doesn't sound right to only do one set of 3 reps, even if it's 90% 1RM. There's no way you're stimulating the whole muscle. Lots of fibers will remain unrecruited, and will not be pushed to improve.
Perhaps you're stimulating the same muscle with several different exercises during the same session, but then you're not really doing "one set".
All this boils down to: you need around 24 ... 25 reps per exercise to really dig into all fibers. Shorter sets = more sets = higher load. Longer sets = fewer sets = lower load.
For whole body training, this strategy leads to 40 ... 60 minutes required per session to stimulate all major muscles. Given 3 sessions per week, that means 2 ... 3 hours per week of weight lifting. That's not excessive by any means.
Basically, I consider all of the above as the gold standard of whole-body strength training for amateurs. Using these principles (and others) I transformed myself from a pencil-neck into the guy who bench presses 100 kg (220 lb).