Rule of 2 and 4: If you call on the flop, must you call on the turn?

[orig!naL]

Ok say we have a hand similar to this:

SB: $21.50
BB: $21.45
UTG: $36.70
MP: $13.80
Ju5tin (CO): $25.00
BTN: $26.25

SB: $21.50
BB: $21.45
UTG: $36.70
MP: $13.80
Hero (CO): $25.00
BTN: $26.25

Preflop: Hero is dealt Ad 9d(6 Players)

2 folds, Hero raises to $0.85, BTN folds, SB calls $0.75, BB folds


Flop: ($1.95) 5d 9d Jh (2 Players)

SB checks, Hero bets $1.50, SB raises to $6.45....

Assume only remaining D's as outs.

Given the rule of 4, we have ~36% (9x4) of hitting an out. Our pot odds (~2:1) tell us we need to hit an out 33.3% (1/3*100) of the time to be profitable.

Given this, it is profitable to call. <u>My question is: Using the rule of 4 provides you with the odds of hitting an out BY THE RIVER, so if we are calling a flop bet, we must call a turn bet correct?</u>

The rule of 4 seems a little odd if you are just going to fold when you don't hit an out on the turn.

Can someone please clear this up?