As a general rule, the more advanced the startups are in the finalists, the less time you need to spend in bootcamp. In an idea-stage accelerator, in an accelerator which is more risk-averse, or in an accelerator with part-time participants, you probably want to run a longer bootcamp.
BlueChilli’s AmatilX accelerator is starting its bootcamp today, running 40 teams through a two week bootcamp. They’re idea-stage startups (pre-product) and for some, this is their first exposore to working in startups. Not a bad thing to spend a bit more time with them. If they’re not accepted into the final cohort they at least leave with a lot of useful stuff they can use to keep working on their idea.