I agree with Garrick, the real question is "what are their post flop tendencies?"
loose players tend to call down post flop if they hit "anything". In spots like this, they will read you for "AK" because that is the only hand in the entire universe you would ever raise with preflop, so they read you for AK and exactly AK and call you down with any value hand as long as no Ace or King is on the board.
The above is most loose fish.
The key to a triple barrel line like this is targeting players that have demonstrated that they DO NOT think like the above and can read you for a strong made hand and fold accordingly. Imo, about 25% of the LLSNL player pool has this ability (as long as you have a strong image). The remaining pool of players are calling you down after they call that flop bet.
FWIW, I completely removed the triple barrel line from my game at 1/2nl, 1/3nl, and 2/5nl levels. Once they call a big turn bet and have 50% or more of their money in the pot, they simply are never folding river unless a big scare card hits. And hell, even when the big scare card hits they still aren't folding enough for triple barrel bluffs to be profitable.
Had a funny hand that illustrates my point last week in the 1/3nl game.
V has A
J
in MP
Hero has A
9
in the BB, 5 way limp fest, I check my option
Flop(18) J
7
3
chks to V, V bets $15, 1 caller, I call
Turn(63) 8
I chk, V bets $45, folds, I call
River(153) 2
I lead out $80, V slams his fist on the table and calls
I show the A
9
he says, "I knew you hit that stupid diamond" and then he shows the AJs
I keep these sorts of hands firm in my mind when I'm thinking about triple barrel bluffing in LLSNL. Unless you are targeting players who have DEMONSTRATED that they can think at Level 2 and have folded when they read someone for a bigger hand, you are lighting money on fire.