That last point deserves to be underlined, because coaching practice quietly agrees with you. A lab test on day one back mostly measures plasma volume plus last night, plus the anxiety of being tested. Coaches who retest after three or four easy sessions aren't being patient, they're waiting for the fluid side to refill so the number actually says something about the muscle. The muscle story is also slower than the panic. Capillary density, mitochondrial enzyme activity, the neural side of strength, those fade over weeks, not days, and they don't register in an early test at all. So the day one reading is worst case and least informative at once, which is a bad pairing for motivation. Tightening conditions beats adding metrics for a reason: more variables means more ways to fool yourself. One route, one pace or wattage, watch heart rate drift over a week or two. If the engine is intact, that drift collapses fast as blood volume returns and the trend stops looking scary. If it doesn't, that's actual signal. The honest limit is that home trends can't separate a genuine loss from a badly timed test unless you've built a baseline the same way before the break. Most people haven't, so the baseline is the real gap, not the metric.