The number of callers preflop should also be a factor.

Say you raise $1 pf and get 4 callers. You hit your TPTK on the flop. You have a $5.25 pot and decide to bet 2/3 of the pot ($3.50). 1st opponent (big fish) calls with poor odds. There is now $12.25 in the pot with 3 opponents still to make a decision.

$3.50 to call with a OESD or flush draw is now starting to look like pretty good odds, and with every caller the odds get better.

So you end up in a 3 or 4 way pot with a pair. Don't fancy your chances much.

A pot size bet may have discouraged the fish from making that 1st poor call.