How many warm-up sets is enough — more isn't better
Warm-up sets with gradually increasing weight before a working set serve a specific purpose — prepping the nervous system and joints for the load ahead without generating unnecessary fatigue. The problem shows up when warming up becomes excessive: too many warm-up sets, especially ones close in weight to the working set, build up noticeable fatigue before the actual working sets even start, hurting performance right where it matters.
A reasonable guideline for most heavy compound lifts is 3–5 warm-up sets with gradually increasing weight and correspondingly fewer reps, with the last one close to working weight but not taken to failure or even noticeable fatigue. Adding more warm-up sets beyond that usually gives diminishing returns — the joints and nervous system are already prepped, and the extra volume just spends a resource that would have been better used in the working sets.
A warm-up should feel like preparation, not a mini-workout in its own right. If there's noticeable fatigue after the warm-up sets before the first working set even starts, that's a sign to trim the warm-up volume down, not add more.