In addition to what Rachel and Lindsay said,

Sometimes this fatigue became my speed limitation, instead of aerobic/anaerobic capacity.

These are not separate. It sound like you’re well above your AnT, so the clock is always ticking in that context.

On two separate occasions, when keeping the same pace of other very well trained buddies, fatigue became cramps.

“Other well-trained buddies” almost always means “people that go too fast relative to their aerobic abilities.” I wouldn’t worry about it.

Instead, find out where your own fitness is at, and train accordingly.

They are connected systems, but with relative strengths. If the CV system is stronger, then the legs will tire sooner and have a harder time demanding high heart and ventilation rates from the heart and lungs. If the legs are stronger, then HR will be high and breathing will be the limit. The relative strength also depends on the context.

A given training method doesn’t train all systems at once to the same degree. We’re limited by the most scarce resource.

It’s very much Liebig’s Law in action.

Use the search field on the home page to search for strength training and you’ll find plenty of resources that explain the what and how.