There is no "too long". Your beer will always be good, even if you don't do a secondary. Heck, maybe fermenting in a primary only will give your beer the extra zing that makes it special. There are no rules.
Par example, we've been making a bunch of beer lately and I need some more kegs, so all the primaries, kegs and secondaries were full. So a couple of batches had to stay in the primary at least 3 weeks. The Pale Ale done this way was just awesome. Maybe one of the best. It had a very British character...maybe some esters and whatnot from long yeast contact, but in Belgium they call "off flavors" a style
In my opinion, best practices for the cleanest tasting beer is to rack to secondary within one week. But, this is definitely not something that can make or break your beer. By all means, brew this weekend! Brew every weekend!

Racking in 10 days is no biggie.
Cheers!
