As said above, flexibility is key. And knowing your class, which will come with time.
Under normal circumstances, I usually mix them every day depending on the needs of the day but do at-least-weekly carousels to mop up gaps - these are grouped by the gaps I want to fill so are broadly by ability but change constantly. And most work is tailored to be low-threshold, high ceiling (e.g. find a way, find more ways, prove you've found all the ways).
Ability tables are okay on a very short-term basis. I haven't used them since my NQT year (and moved away from it even then). The thing is, ability isn't a static thing - there are lots of aspects to it. Some kids can reason but don't know their times tables; others know their times tables but can't read the questions; others can do both but have low confidence; and then there are ones who are bright but will crib off their neighbours if you put them with the bright kids. Pure ability is rarely the main concern, and even when it is, kids often have different strengths and weaknesses within subjects so it depends what you're working on. Usually better combinations become apparent: e.g. a numerate but quiet EAL child next to a reading-loving mathsphobic child.
For your high-highs, working with other GDS+ children can become a crutch (especially where you have strong personalities with a reputation for being right and people defer) but equally you want them to have people to spark off now and then so I try and give them something meaty to collaborate on maybe once a week. If they really are off the scale and sail through everything, be aware of what problem solving skills you want to develop (Everyday Problem Solving and Reasoning is great for this if your school has it).
If parents are cross about a lack of GDS grouping, probe for the issue that underlies their complaint. If they want the child to be with the HA group, is this because the child doesn't feel stretched, or because the child has been with these kids before and feels nervous without them or feels like they've lost prestige... or is it just the parent projecting and the child is actually fine? If you work the GDS kids hard and keep them stretched, they generally won't have time to complain about their seating!!
Don't underestimate how much you can inspire a less-confident child by having them work with more confident children if you can identify a strength of theirs - for example, I had a girl last year who had great times table knowledge but was very behind in general. I asked her to join a group of confident kids for a times table investigation. I didn't think twice about it really but at parents' evening mum told me it was a huge deal for her to be doing a project with "the clever kids" -- apparently this had never happened before!
My experience of class-by-class primary setting is that kids aren't evenly distributed and the vast majority are in the middle -- splitting them doesn't do much as the extremes are still extreme relative to the set and you just create problems in the middle. In secondary where you can split more ways, there's doubtless more benefit to the top and bottom but I suspect in the middle there's room to consider group dynamics beyond blanket "ability".
Anyway, good luck with your NQT year. Crazy time under any circumstances but especially now. Pace yourself and be kind to yourself. :)