Do caster out of combat options matter?

[clash]

Yeah, and in that same scenario if one of the PCs could cast plane shift they may have saved maybe a session and who knows how much in game time.

But also consider the "not so big barriers", players are exploring a unknown jungle and get to a huge chasm with a city floating in the middle, is flight the only conceivable option to get there? No. Is it the simplest one? Probably.

And there's also all the sidetracking that ends up happening, maybe while doing the research for the planar portals the PCs come across some strange happenings in Candlekeep, and now the plane crossing adventures are on hold in favor of mystery solving in Candlekeep, because that's more appealing now.

You say it like sessions spent researching portals and looking for a sage are wasted sessions? Or time spent side tracking is time not playing the game. I think it's quite possible the plane shifting actually takes parts of the game away from players that enjoy it and whether it does or not I wouldn't say there is a real advantage to one approach or the other.