First and most important, your kid will not be the same as someone else's and so you have to work around them.
That said, DD has been at 10 months, 34 months, and 40 months so far. We learned when she was 10 months old that she does best with a real rest in the room. She would sleep in her stroller but we made the mistake of taking that for granted on our 1 HS day that trip and tried to push through without a midday break. She was an absolute disaster by the time we were at our dinner ADR and we ended up skipping fantasmic even though we had done the package because we just couldn't keep her out any longer.
Yes, getting back to the resort is time consuming, especially if you have to use the bus, but for our DD, it was the best choice. It's not just sleep because as I said, she did that in the stroller, but it's getting out of the heat (2 of these trips were in March and one in November but still plenty warm some days...coats and scarves others, that's Florida for you) and all of the background noise and stimulation.
That said, we do not do a rest day. We do the midday break every day of the trip and that's all and it seems to go just fine for us, usually with 7 park days, with our arrival day being for Disney Springs and resort exploration. Both my parents and DWs have a pool as well as the one in our neighborhood and DD has weekly swim classes so while she loves being in the pool, it's not something we really do at Disney because we are there for the parks. Take that FWIW and enjoy your trip in whatever way is best for your family.