I’m a single mum and I love the time that I don’t have them. I see my friends, do things that I couldn’t with them in tow, stay up late, sleep as much as I need, watch what I fancy on tv, work extra hours, eat what I fancy, go on dates, and very recently have been able to start using the time for holidays. It’s lovely and very much a positive of single parenting - I get more time to myself than a lot of my couples friends.
I think that there are a few things that make the difference for me.
Their dad doesn’t have them a lot (One night in 14 plus 4 or 5 full weeks a year) so it feels more like free babysitting for me rather than them having two homes which I would find harder.
Their dad is a reasonably competent person (although not a great parent) so I’m not worried about their safety and he’s a real Disney dad so they always have a good time. When they were small I tried to stay within a couple of hours drive but now that they’re primary age I’m confident that they’d figure it out together if they had a problem.
He doesn’t want them more so there’s no pressure/disagreements/fights for custody. In fact, given a completely free choice he’d probably have them a bit less so there’s no sense that this has been forced on me, there’s no court order, and I have control over when they’re there (to a reasonable level)
I am lucky that I earn well enough that I can afford to pay for things for me without it effecting the childrens quality of life. I suspect that it’s much harder to enjoy that time if you’re trying not to spend anything so that you can save for things with the kids etc