The chart is good as a general guide to follow, but it's important to know the parameters of the particular battery your using with a mech. Essentially a mech is just a way to conveniently complete a circuit and little else, so the battery is everything.
Check out batterybro and look up the specs of the battery your using, then use
ohms law to figure out the amps your going to push with a build at 4.2v.
For example the 25r is a popular reliable battery, and it has these amp ratings (batterybro);
"Max.
continuous discharge current: 20A"
"Safe
pulse discharge ratings: 95A < 0.5 sec, 65A < 1 sec, 40A < 5 sec, 30A < 6 sec"
Ohms law say's;
0.3 ohm build = 14A
0.2 ohm build = 21A
0.1 ohm build = 42A
Above 20A with a 25r your getting into the realms of pulse ratings (caution), so you need to know what your doing to avoid possible venting.
Hope this helps.
(I haven't read the whole thread because I'm lazy! So my apologies if I'm going over what's already been said by others or stating the obvious
)