Can you guys
@ClaudeR and
@Anna C tell something more why TGU is not a good choice for GTG?
Sure, but let me first say what I'm
not saying... I'm
not saying it's a bad idea to do TGU in a GTG manner (i.e. a rep or two throughout the day). It's always a good movement to do, and practice is always a good thing. I'm just saying you're not as likely to get the advertised benefits of it -- the specific and rapid strength gains that GTG can deliver with the things it's more suited for.
GTG is about neuromuscular efficiency; about practicing the skill of strength. A pistol squat, OAPU, pull-up, etc. are perfect for GTG because they require pure strength and you can do them almost anywhere so it's easy to fit in GTG practice. You could also do it with deadlift, press, squat, etc... but they are less convenient because they require equipment, plus with these it's less likely that you'll be able accumulate significant volume in multiple GTG sessions of half what you can do throughout the day almost every day, because they are bigger, compound, more fatiguing movements. With GTG you're generally practicing a skill that is not very overall fatiguing for the body.
The TGU isn't really about maximum force production. It's about time under tension, a lot of challenging movements all in one combination, moving skillfully under load, tension and relaxation at the right times. It does require strength and it will make you stronger, but it's not really a pure strength exercise.
Also, GTG is specific. It makes you more efficient at doing the specific skill. Why do we do TGUs -- to get better at TGUs? Generally not... It's not a contested event anywhere, not a battlefield skill, doesn't create any specific hypertrophy... They are more of an exercise with general benefits; a little of everything. You do want to get better/stronger at them (i.e. progress to being able to do 5 each side with heavier weight, as in S&S), but neuromuscular efficiency isn't generally the thing holding you back, so a standard practice is probably more beneficial towards your goals.