Am I right in thinking with my non-immigrtant O i still have to leave once every 90 days and renew the thing once a year?

Am I right in thinking with my non-immigrtant O i still have to leave once every 90 days and renew the thing once a year?

Provided it is a multiple non-imm O you have to leave every 90 days. If you return just before the expiry - date you will get another 90 days, means you need a new one after nearly 15 months.