Lamp bulbs need to be replaced as often as normal household bulbs that are on all day do. So every few months.
A UTH will rarely need to be replaced. It only needs to be replaced if it malfunctions and stops heating up properly. It would be a year or two before this would happen to a good UTH.
I prefer zoomed UTHs for single setups and reptitemp 500r thermostats for single setups.