How to gauge frequency needed to keep bathroom clean at retail store

I clean 2 single bathrooms, unisex with one toilet and sink in each. We have a very high volume of use. It’s a thrift store but we support a local non profit and have a lot of volunteers and employees. It doesn’t (quite) meet the threshold for legally needing more stalls but its very close due to the customers also using them. I don’t know how to estimate how many people are using them without one of those door counter things. I think because of the heavy usage it really needs more than one person one time per day cleaning them and occasionally a day skipped when I am not working.