Through traffic or no?

[Pete]

Back in the Stone Age, when computers did not have clocks in the taskbar, I made my own clock routine to display the time. The problem was it needed to be constantly looped to keep the time displayed accurately. To accomplish this, I made all my sub-routines flow-through routines. No matter how nested the routines became, the program always flowed back to and cycled through the main. Now that was a PITA when it came to variable management, but at least I didn't have to place a clock call in every sub-routine that had loop routines. 

How about the rest of you folks; what method do you prefer to use for large projects when it comes to keeping the flow in each routine or always passing control back through the main? Currently I favor avoiding flow-through routines.

Pete