I agree regarding 'teens need you more than toddlers' - I've two teens now & 1 pre-teen & I'm mentally & physically more exhausted than when they were little (and I've been a single p parent since when they were small!)
Their emotional needs are more intense, but also they are busy - mine play sports & we have commitments 7 days a week. Some of them they can get themselves to, but apart from lifts, I want to be there to support them & be part of it.
However, as others have said, they don't need the obvious physical care of small children, and if you want to work full time then you should. There would be a lot of time when they're not around & don't need you!
I've always worked full time, more or less, partially as I must, but also because I want to.
I suppose it's a personal decision but I can't see the problem with being alone for a few hours, or even long days in the summer. Mine had jobs to do, met friends, went on outings. I was completely fine with that.
What does cause me stress is the mess & scale of eating that goes on on the days I'm in the office & they're in the house alone! They are meant to tidy up but it doesn't work all that well. I dread coming in to it.