If you eventually plan to take all four parts of the exam, you can check all four boxes. After you pass one part of the exam you have 18 months to take and pass the other three parts. See the 18 month requirements below (How do I calculate the 18 months rolling window?).
Though you may not notice, as bulbs age they don't generate as much light as when they were new. That means your headlights may still work after five or six years, but they may not be as bright or illuminate as much of the road as they used to.
Cheaper ILBs last 750 to 1,000 hours or less than a year of normal usage. Long life span ILBs can be up to 1,500 to 2,000 hours, but they cost a lot more. Still, they last only about 2 years with normal use. Fluorescent & CFL Lamps. Fluorescent lights and compact fluorescent lights (CFLs) have a similar burn out scenario as ILBs already discussed.