2011 F150 Fuel injectors
 

How often do they need serviced?

Not sure what you mean by serviced. Usually a intake and injection cleaning should be done every 15-20k

Cleaned, I suppose. After the initial cleaning at 20K, I should have it done at 35-40K now?

Yes. Should always run some 93 thru the system every once in a while as well. I run 93 all the time since my tune and I've never had an issue. The newer trucks don't have an external fuel filter so you need not to worry about changing that.

Intake and injection cleaning is not required - especially that often. No need to run 93 either, just don't give it a steady diet of cheap offbrand gas.

What's a lot more reasonable is a Techron treatment in the gas every 6 months, and an intake cleaning when you change the spark plugs.

OK, I'm curious. What would running 93 octane do for a truck engine?

Nothing unless you are advancing your timing (tuner) or are boosted. Well I take that back, it makes running your truck engine more expensive.