Both of these are incorrect. Imagine 1 mineral patch. 1 worker mining gives 1 “income.” 2 workers mining gives 2 income. 3 workers mining gives about 2.5-2.8 income (depending on if it’s a close patch or a fat patch). 4 workers mining gives the same 2.5-2.8 income.
Each mineral patch is essentially isolated from the others. Adding workers is a linear decrease past 2/3 saturation, not exponential. And at max saturation, additional workers give no benefit
Also incorrect. The 30th worker will help all the way until the point where workers get about 55% speed increase. At this point, workers 21-30 are all useless at the same time.
Stetmann with blue field (without mastery) starts at almost max saturation for most maps: 14/21. But adding 1 worker doesn’t bring him to max: he still needs 21/21 in order to reach max mining income. However, if you have enough points in the stetzone mastery, 14/21 will be equal to max saturation.
I could obviously be wrong about these, so I ask you to prove me wrong