Here's the reason most m/c's require bench bleeding....

The pedal will not often stroke the piston in the m/c all the way to the end.

Bench bleeding has no such restriction, you can push the piston all the way down the bore and no air is likely to be trapped in the end of the bore causing spongy pedal syndrome.....supposing you have correct bleeding hoses to bench bleed.


.

__________________
[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."