The phrase "checkout" isn't even part of the regs. That's strictly a flight school/insurance requirement. To fly a 172 you need:

1. To be rated single-engine land and current medical
2. Have a current BFR
3. 3 landings in 90 days in category/class (only if you want to carry passengers)

That said... what's legal and what's safe may be 2 different things if it's been a LONG time since you've flown a given model.