you only need to polish once a year. ideally after the real grotty winter weather has gone. then start to build up your paint protection over the course of the year ready for winter.

maybe even less that that if you use a good wash process and protect the paint well. polishing every week, even with something that's not that harsh such as ag srp etc with eventually see you needing a respray due to wearing through the top coat or colour layer if single stage paint.