Playoff does not count as service time.
I often carry 9-10 pitchers and 15-16 hitters in the playoffs. I don't want some shitball LRB pitching in the playoffs. So I fill out my roster with specialty players. D heavy, LH power, Speed/BR, etc, etc. Actually won my first WS with a PR in the 9th of game 7 who never played a non-roster expansion inning in his career. One caveat, a couple of extra innings games will smoke your staff and you can't fix it until the series is over.