I was thinking of you as I wrote my response - as I think you and I are both in the camp that we will take any time we can get with our kids.
Yes, without a doubt. When H and I were hashing out our S agreement, he made the observation that "if we (do X), then neither of us will ever get a free weekend." Boy, that fried me. I replied along the lines of, this is about our kids, not our social lives, I don't get free weekends now, and if I never have one again, so be it. Not very validating, and to this day I don't care. And truth is, I never have a truly "free" weekend, D17 rarely goes to her dad's place (I think she's been there 4 times in almost 5 months) and she's never been on a weekend. Now, I obviously don't need a babysitter for a 17yo, but I also don't pass up available weekend hours with her. If she's home, I usually am, too.
Anyway, good luck Raliced, I hope you find the best way to address this. Do what you feel is best and don't worry about STBX reacts.