Nope. Whatever the print needs is the amount of seconds I use. I fail to see why this number should have any other criteria.

I use a metronome, so 1/2 second is about as precise as I can get.
Using the f/stop method I aim for exposure times in the 20 to 40 second range, in order to be able to smoother apply burning and dodging maneuvers, and it effectively eliminates any inconsistency the use of a metronome introduces.