For all visits, but especially the first, the Phazon Mines are an endurance test.
Save Stations heal all your health in this game, so they couldn’t put them here with the frequency they tend to have in games like Zero Mission, because that would remove the challenge. That said, the Phazon Mines have a lot of text to scan and/or read, so they take forever to get through if you’re actually reading everything. Even if you’re not, the span from the intro cutscene room to the Power Bomb room is quite long, and the regular enemies do a lot of damage. It’s a good thing the poison room is in there!
One thing about Metroidvanias is that huge swaths of the games are not spent doing boss fights, but running around and grabbing incremental upgrades. Transit in this game is not the greatest, especially with that one-way elevator at the back of Chozo Ruins, so as I continue to progress there will be more and more time just going from point A to point B. It doesn’t make for the most interesting content, but since I still have things to grab along the way sometimes, I’ll still keep it in the video. Just, you know, sped up, like everything else that isn’t a boss fight or the last puzzle before a major item.