The idea of measuring everything and acting on the numbers you can get is from the 19th century. Managers have been doing that same kind of practice since then, with the same kind of result (it's a very reliable result), without a change.
He did experiments where he would have workers shovel piles of ash from one side of a line to the next, giving them a new shovel size each day. Found that the ideal shovel size holds 21 pounds [1].
The ideological assumption of his work is that management exclusively does the thinking and the workers exclusively do the doing. This falls apart when the workers have unique knowledge and insight that management does not have.
[1] https://www.mentalfloss.com/article/63341/frederick-winslow-...
AKA every time.
AFAIK, Taylor himself wasn't nearly as radical about doing measurements and only acting on them nor about managers deciding everything and not listening to the workers as Taylorism preaches. His work was one of the many, many management theories that was completely modified to appeal to incompetent power-hungry wannabe dictators (and yet blamed on the person proposing the original theory).
When you do things right, people won't be sure you've done anything at all.