I’m a mom of six, married 20 years.
My best advice - it’s not mass. It’s the whole schedule issue. She’s probably burned out or in the process of burn out. It happens. Raising a large family is tough beyond belief, and the stress on the mom - no matter how much help from dad - is huge. And I suspect you’re probably pretty stressed too.
So forget figuring out mass as an isolated thing. To you it is, but to her, it’s probably not, even if she’s unaware of it. The being late is a symptom.
I’d suggest you both look at making your lives less stressed and approach the entire weekly schedule that way. Understand that what stresses you (the style of attire at a parish, being late) may not be a stressor for her - and hopefully she can see the same thing when it comes to you.
Does everyone have enough time in your family life to relax, play, be alone, and have family time - both as an entire group, and one-on-one time with each other? And remember what counts as “enough” is based on each person’s age and personality - not what just works for one person.
I suspect, based on my experience, that not one of you is getting all you need in all those areas - and so this mass issue may be coming into play with it being a relief for you to have everyone together and attending Sunday mass at that location, while it is a relief for your wife to have a much smaller number of the kids with her at on Saturday at the closer location.
And if that’s the case, neither of you will be happy about any mass arrangements until peace in the rest of the weekly schedule is found.
Again, just extrapolating from personal experience, and what I’ve read throughout the thread. I hope you are both able to work out something that brings you both peace.
Thoughts and prayers,
CJ