If my kids are tired, I don't make them more tired and fussy nor take them to the park plus grocery shopping and I don't give them the chance... to debate that.
I just tell them what we are doing, and that's it.
If they fuss or grumble, so be it.
I tell them, too bad, you are overtired, we are going home and that's it.
My kids once had 2 playdates back to back, overall by the time it all finished it was like 12 hours. They were TIRED. I did not, do anything remotely even, to get them more tired the next day nor on that day.
They were, pooped, out.
If my kids throw a fit.... I tell them "yell, scream all you want, when you are done let me know... we are STILL NOT going to do that..."
And they quiet down.
I tell them "Even if you scream or fuss, we are NOT going there, NOT doing that, NOT at all."
That's it.
The thing is: not everything is a debate, not everything is a negotiation, not everything is a choice, not everything is up to the kids. I AM THE MOM.
That is it.
And having a tantrum about something, is NOT going to fly with me.
I still say, no.
THEN the other side of the coin is this: As a Mom... IF you know that playing for 6 hours straight, is going to make your kids tired and fussy and tired even the next day and they have to catch up on their rest... then, do not do that. Don't have them play for 6 hours straight. It is up to us, the parent, to regulate... the kids. So if you end up with overtired fussy kids, it is our "fault" too.
For me, I knew... that those 12 hours my kids had playdates for... WOULD make them majorly tired. But I let them have the playdates... because they were off school on that day and the next day was a weekend. So it was fine... I was FULLY aware... of its impact on my kids. ie: they would be tired from it.
Thus, I redid my plans for the next day, with them and even that night.
That is my, responsibility and my knowing my kids, cues.