Most common is every three months for two years, then every six months for two years, then once a year, probably for life.
Eyona ixhaphakileyo yile yenziwa rhoqo kwiinyanga ezintathu iminyaka emibini, kulandele rhoqo iinyanga ezintandathu iminyaka emibini, kuze kube kanye ngonyaka ubomi bakho bonke.