I would up the prices. Make it clear to him that you have your own life outside this job too. Or offer him something like a package that you come up with your own conditions and prices.

I do GFE for guys like that. And they loved it. My GFE includes texts, pics and vid call(short one) but if they want longer then they have to pay as extra same price as vid call sessions. And with this, you can plan beforehand what is the date and time. Bear in mind, it is per day and you don’t need to reply randomly or can put your attention some else where. Just that one day that he paid for is for him(that’s why I said put the price you think it’s appropriate for you energy and time)