Yes, seriously. At typical low/slow temps one can expect 15-18 hours of cooking for butts of typical size, i.e., ~7 or 8 lbs.
You can start later if you bump the cook temp (think closer to 275 than 250); or you can do that and plan on foiling (either late night and stick them in the oven) or in the early a.m. and stick them in the oven or leave in cooker); or, unless needing meat for 80 people, you could do smaller roasts - 4 in the 7- to 8-lb range, started a bit later and cooked 235-250. Or halve them, as ron notes.