Depends.
I can usually have a new campaign up in a day, but taking it and branching it off into multiple traffic sources is what takes time.
Also, going the scatterbrain method and making 7 campaigns each day on varying niches isn't going to get you anywhere. I started about 4 months ago, and so far I've made campaigns for 20+ verticals, 40+ campaigns in all. Only a select few have generated significant profits, and those few were very closely related.
The time it takes to make a campaign also varies by traffic source. Starting a new campaign on search may only take an hour to find keywords and generate a dozen or so ads, but on social, generating 2000+ ads precisely matched to varying demographics is going to take longer.
And like Gopher said, media buys take longer to setup.