Yeah, the 4% is for the year, not per withdrawal.
It is possible that your accounts could rise 4% in January, and then another 4% in February, but that doesn't mean that you can take out 8% for the year and call that a 4% withdrawal rate.
If you take out the money monthly, you take out 1/12 of 40K. If you take it our quarterly, you take out 1/4 of 40K. If you take it out annually, you take out 40K. How much your accounts rise that year in value has absolutely no impact on how much you take out, if you are trying to use a 4% WR.
If you don't want to use a 4% withdrawal rate and instead want to try something different, then I recommend that you read extensively on the matter to better understand the impacts of various withdrawal rates and how to execute them.