The other part I'll add is having a team of multiple stage managers who all call the show so you rotate. Last show I did, 3 stage managers:
*The PSM would call 2 shows a week; the other 6 shows a week the PSM would have free to watch/note the show, do paperwork (schedules, organizing press events, reports/payroll) or rehearse new company members. The PSM would not run the deck.
*The 1st ASM would call 3 shows and deck when the other ASM called; the other 2 shows a week (when the PSM was calling) the 1st would do paperwork (sign-in sheets, update track sheets, help with payroll, order office supplies, create new hire packets, order playbill stuffers, etc).
* The 2nd ASM would call 3 shows a week and deck the other 5. Every so often, the 2nd would get to take a show off to watch from out front, do paperwork, etc.
(This is just a template... other teams sort it out differently. On one show, the PSM was the original 1st (ie. set up the deck track) so would occassionally run the deck, just to stay in touch with it/because she was bored. I've also heard tale of shows (something like Les Miz) where the PSM only called once per YEAR (that's amazing to me... but to each his own...)