Multiplier - how much is enough?

I'm not sure of the desired percentage, but I know what my goal is.

I have about 205 220 characters and still have the 1-hour premium task of "Hike Up a Mountain to Complain" for Kwik-E-Mart Headquarters. I'm pretty good at remembering to get everyone employed within an hour of their finish many, many times a day. Everyone gets an 8-hour job overnight (with the exception of The Parson and Fatov, who each start 12-hour jobs around 7-8PM).

I'll know when I've got enough bonus when each 1-hour job cycle results in a donut window. Right now, each job cycle nets about 60% of an XP cycle and my bonus % is about 1340 1347 not counting SH.