It depends usual a few evenings. But every so often I'll have a base (milliput for the paving) and undercoat session.
At the moment. I have a few foundry n'ver do wells undercoated. The Lycaon Faction, Cedric and the Ape man based awaiting undercoat. I just then pick up a few figures and start whilst ones drying do a bit on the next and so on.