It depends on how busy the site it. A moderate volume car wash (gross sales <100K year) can often get by with a single morning visit most days, with a second "touch up" visit on Friday, Saturday, and Sunday, especially during peak seasons. I expect the primary visit to take an hour on average to wash down bays, dump trash, sweep and blow the lot, pick up trash in the landscaping, and look for any problems that need my attention. The second touch up is often 15-30 minutes. Washes grossing more than 100K will probably benefit from two visits a day, seven days a week, and the possibility of a third mid day visit on peak days, or even a weekend employee. low grossing washes (<50K) can usually get by with a single daily visit, especially if there is a camera system in place.
My preferred clean up schedule is the main morning visit between 6-9AM, and an afternoon touch up around 2-3 pm. If a third visit is warranted on peak days I try to make it around Noon. Sunday AM heathens who skip Church and clean up their car instead can be quite the mess makers.
I come into the site and make three visits on average weekly to take a closer look at things and restock the vendor weekly.