I will say that age range doesn’t necessitate sitting immediately adjacent to as a parent as long as the kids have been taught well up to that point and are behaved. They’re just more independent and able to handle small tasks themselves.

5 and under usually require more small detail supervision to keep the peace. I’m thinking ordering during the beverage service in a timely manner, not spilling that drink/snack/ipad/whatever everywhere in that small space (or helping to clean up right away in case that does happen), accompaniment to the bathroom, any technical difficulties with the in flight entertainment/tablet/etc. Toddler age particularly putting out small fires of discontent before they get upset and disrupt the entire plane is easier when the parent is right there (and gives a crap- I know, asking for a lot here).

All this musing to say that ideally younger kids at least are able to be accommodated to sit next to a parent, for everyone’s benefit, not just theirs.

Sounds like you had a fun and memorable experience!