Its such a lovely time, and goes past MUCH too quickly!
I always saw the zoomies as them trying to squeeze that last bit of excess energy out before they finally flop!
, and a good signal for calling an end to that play session. As long as she‘s playing „nicely“ and you‘re both enjoying it, then there‘s no reason to worry about limiting it, once any biting, snapping or grumbling occurs then that‘s usually because they‘re getting tired and fractious but you can judge that yourself.
Its a good habit to insist on play on your terms (n.b. what I say rather than what I do
, even at 5, mine knows how to give me that look!), - so you decide when play stops and starts. I usually end play by saying „Enough“ and simply stop. You then have to endure that „oh woe is me“ look for the next ten minutes but they do learn in the end!
If she plays on her own, then that‘s brilliant - so many dogs can’t - don‘t fall in the trap of feeling you have an obligation to entertain her all the time, they do need lots and lots of sleep at that age.
Its also an idea to start introducing a few mental games - sniffing out treats etc, that will keep her occupied and tire her out without her getting too wound up.
Sounds like you‘re doing really well so far!
Keep us updated!