For deployments, for upgrades, for setting up testing/staging machines. We picked it because it's agentless (just seems to self-evidently be better for our scale) and written in Python (the devil we know and love). Ours is a reasonably stable and a fairly small environment (~40-50 hosts, mostly containers), and it has been a very good fit.

Granted, moving from wiki pages and ad-hoc scripts to any system would have been a big improvement.