As always, very helpful. Thank you!
I wouldn't recommend a specific number of coats for primer or the colour coat, it's more a case of how many coats you need to get a full, even coverage on all surfaces, while only putting the primer/paint on in light coats.
The Bruiser in the example took 4 coats of colour, but that was slightly unusual in that it was a dark colour (with not a lot of pigment in it) over grey primer, with the added complication of it being metallic (so any runs/sags would probably neccessitate a complete do over, rather than later correction).
3 coats would be more normal, 2 would probably be somewhat unusual (but might be the case where the primer & colour are closely matched - white over white primer, deep red over red oxide, etc). Only one coat would probably mean inadequately light coverage, or - more likely - far too much paint on in one go, very possibly forming a paintjob that never cures properly.
Primer you can be a little heavier handed with as it doesn't form a skin in quite the same way as colour - 1 coat might be too much, but 2 would be more normal. 3 would be unusual IMO.
