--FWIW I *never* use 4-flute taps; too prone to breakage, heh.
2-flute taps do for most everything and I use them manually or in a
Tapmatic all the time. A 1/4-20 tap is big enough that it can be held
by a VSR drill and this is damn handy for large work that needs lots of
holes tapped.
--The real secret tho is to have new, good quality taps and to
use lots of the right lubricant. For steel, brass, aluminum etc I use
Cool Tool II. For stainless I switch to Moly Dee.

--
"Steamboat Ed" Haas : You just can't beat
Hacking the Trailing Edge! : cruisin' in a steamboat
http://www.nmpproducts.com/intro.htm
---Decks a-wash in a sea of words---