Are most of your projects one-time or maintenance?

I’m curious about something. If you’re an independent contractor, consultant or freelancer, are most of your projects one-time gigs or do they more frequently involve long term maintenance? There is a lot of different thinking out there about how to handle ongoing work: batch it up and get it done all at once (and pay for it in one chunk too) or spreading it out over a longer period of time (the pain isn’t as severe, but lasts longer).

Most of my projects start as one-time gigs and then evolve into ongoing maintenance work (assuming the client is pleased with what has been produced, which they generally are). I can think of only two instances where a one-time gig was just that… one-time… and didn’t involve ongoing maintenance. What has your experience been?