The way to think about it is like this. You will hit
two pair on the
flop 2.2% of the time,
trips 1.4% and a
flush 0.8% and a
full house 0.1%, so you hit a big hand on the
flop about 4.5% of the time. Assuming opp stacks off every single time you hit a big hand (and doesn't redraw against you) then you need to be
able to win 22.2x the amount you need to
call to give you
implied odds (ie. you need effective stacks of 22.2x the cost of your
call).
However, opps generally won't
stack off every time so you need to add some extra
implied odds to take this into account. With
ATC the correct number depends on how bad opp is (ie. will he
stack off with
Ax on an A65
flop?) but may
well be 40-50x or so the amount we need to
call.
That said, with
suited connectors there is the possibility of flopping a
monster draw such as an
OESFD which increases the number of times we
flop something worth continuing with. Not sure how to calculate this however, anybody else?
EDIT: The
implied odds calculation above is why min raising preflop is such a bad idea in cash games and tourneys when blinds are low. BB gets such
monster implied odds to
call with any two trash cards and
stack you if he/she flops something nice.