yea, it's a leak to always do any one thing in poker, you should adjust to your opponents like you wrote.

like if i am playing heads up vs a loose passive, i will bet 1/2 or even 1/3 pot on the A93 type flop when i have nothing, and when i have a good hand then i bet full pot.

but against deeper thinkers i don' think it's worth randomizing based on the minute of a clock. just mix up the bet sizes enough where they can't say "oh he bet pot, must be TPTK"