I think with all things, it depends. Speed is not the goal with LSD training, so it would make sense to not do a ton of this if speed is your focus. But even that depends on your definition of speed… is it Rainier in a day? Because alpine-wise, that’s pretty fast for the average Joe, but compared to a 5k run the pace is quite slow.
In alpine fitness, short duration speed isn’t as important, so it isn’t often prioritized except maybe ramping up to a certain goal. Look no further than the now over-hyped/over-sponsored/etc CrossFit Games. It’s common to hear the announcer say “this workout has a 3 mile run, and it’s probably going to crush these guys!”… pretty minuscule distance for anyone who is a runner, and it seems a little silly to be lauding these as ‘the fittest men on Earth’ yea? But as far as the best at doing CrossFit, they win hands-down compared to probably anyone on this forum.
If your goal is to stay active in the mountains and keep doing big days, then I suggest prioritizing low-intensity work. If your goal is to climb sport routes well into your golden years and crank out fast 5ks, maybe back off of the 4h fasted jogs.