I guess it depends on how many sites and how big they are. Most of my sites are 150-200 pages to keep them manageable. Maintenance must always be factored in.
My little slots site still makes some money and I do nothing to it. I spend all my time on my mail order business which has 5 times the moving parts my slots site does, (like customer service, returns, pricing, receiving, shipping, inventory, packing supplies, not to mention creating product listings which are not unlike creating casino reviews, plus all the changes by paypal, amazon,. ebay, google).
My slots site has none of that to deal with other than Google, so compared to that my slots site is easy money.
Running a casino also has a ton of moving parts to deal with.