Varies dramatically. For work, it's quick and easy, and takes about 15 minutes or less - toiletries and makeup live in a suitcase - just suits, shoes, pjs, done. Even if its a couple of weeks, its adding more of those things and some regular lounge/casual clothes.
Other trips can take much, much longer. I started typing out all the stuff I need for WDW, and it's a lot. I can usually get it in a carry-on, but sundresses, sandals, and swimsuits don't take up much space.