I think we see here some demonstration of the damage from these lengthy expert discussions nitpicking about quality of seeing, measuring every single factor of observing etc that we see on the forums. The death of spontaneous observation, and a member thinking that a clear night might not be worth it..
Androux, your dob feels alone in a shed, asking only to be loved and used as much as possible...
More seriously, as Tony and Jon said, you can always find something to be observed even in bad seeing. Most of the DSOs do not ask for high power and excellent seeing. If I would take my telescope out only when the stars are not twinking, it would remain in its closet the entire year. And still, I do a good part of Moon and double stars observation.
My real criteria: is the sky enough clear of clouds?
But God bless you if you have such a weather that you can afford to cherry-pick your nights when the sky is clear, and take the telescope out only when stars are not twinkling.
Quantity does not equal quality. An informed observer is likely to be a better and happier observer.
There is an opportunity cost to wasting time on nights that are forecast to be bad for one reason or another (seeing, transparency, high winds, etc.) That is what the OP is asking about, optimizing the time commitment for the best experience. As I pointed out, there is some equipment prep time involved as well to make use of the sky. It generally isn't possible to have long sessions every night it is clear/forecast to be so, therefore picking the better nights has real value. One has to schedule around life's other commitments, and often that comes down to picking the best night out of two or three candidates.
Taking some time to look at several days worth of forecast and being able to recognize repeating weather patterns can make a big difference in picking the best nights while skipping the marginal ones. That is true for seeing and for transparency/cloud cover. Or one could use the spontaneous uninformed method and burn their time on a poor night instead, and miss the best night. The difference is a memorable observing session, and a forgettable/regrettable one.
It depends on the pursuit, but there are often "clear" nights that are not worth it. Living here has proven that to me 100x over, I would definitely trade the vast majority of the "clear" nights here for a few nights with good seeing--even more so now that the backyard is twice as bright as it was only 6 years ago. If your interest is planetary, lunar detail, or tight doubles (or aesthetics or observing near threshold) then seeing plays an out-sized role. Poor seeing means a poor observing experience. And despite claims to the contrary, it very much does effect small and medium aperture. I have seen that many times in the backyard here. In fact, an 80mm scope works well enough as a "seeing scout" for a night with useful seeing vs.one only fit for quick looks.
I wish that as you suggest I could afford to cherry-pick nights to when stars are not twinkling at all, but that almost never happens here. I have lived other places where it was not uncommon, but with fewer clear nights. And for the type of observing I did in town, I much preferred those steady nights. They were far more productive and rewarding.
To illustrate just how much difference very good vs very poor seeing makes, there were some nights here a few years ago that produced the only fully stable seeing I have experienced in the valley. They weren't clear nights, because there was a wildfire smoke plume high overhead. This capped the night time thermal losses that drive much of the poor seeing during summer, so for several hours the planetary seeing was excellent. As soon as the plume began to thin and shift out of the way the seeing began to decline. This happened several nights in a row.
And this is without going into whether or not what appears to be clear sky at the moment is likely to remain so. This is not as much of an issue for backyard observing (except when one can really only afford to observe one night or another and has to choose.) However, it is huge for dark sky observing where one must pack up and drive out of town. It isn't a lot of fun to have the skies begin to haze over, or go to full cloud just as one is finishing set up. Those are real enthusiasm killers.
There are also dark sky sites that I rarely use anymore because they typically have poorer seeing. My darkest local site is one of them. It is only available for a few months each year and I have had some great sessions there. But I have also had too many that I ended because the seeing became awful (katabatic winds). I realized after a time that with most detail obliterated, there was no point in making poor quality observations of high quality targets. Contrary to popular myth, seeing has a large influence on what is visible in galaxies.