For the most part I agree with you. I definitely see that you stand a much better chance for a good session if the Domme has a chance to plan and prepare herself for it rather then just doing a session on short notice and making it up as she goes along.
On the other hand I think if Domme and sub have an established relationship and the chemistry is good short notice shouldn’t make much difference in the quality of the session. Like with most things I think every situation is different and has its own characteristics.

Years ago I sessioned much more frequently and did quite a few same day sessions although not on one or two hours notice. Now days it seems less of a thing , at least for me. Scheduling for me is very difficult and there are times I get a same day or short notice opportunity to session but my head is not into it. It’s now nerve racking to me to get ready for a session on short notice. I have to think things through and make sure I have the tribute and won’t get caught being somewhere where I shouldn’t be. I like to anticipate the session and at present do not have a solid enough relationship with a Domme where I think a short notice session would work well.