Do you need to transfer the required funds every year for a Thai visa extension, or can you use accumulated funds?

Fellow members, to some this might be a stupid question. After you have obtained your relevant 90 day O /OA visa in your own Country, in my case U.K., when it is time to apply for the yearly extension, be it retirement or marriage, I understand it's a requirement that you show you have the required funds for the 'seasoned' period, but in subsequent years do you have to transfer the required lump sum funds every year, or can it be an accumulation..

E.g. If someone transfers, let's say 800,000b , its ' seasoned' and applies for extension without any issues, then during the subsequent year they only use, let's say 500,000b leaving 300,000b excess. Do you have to transfer anther 800,000 or 500,000 for the seasoned time... hope that made sense , thanks in advance 🤑