Not everything exists within a stagnant vacuum. If you're not clarifying from start if the healer is good with big or small pulls, then their reaction from the initial pull can tell you what you need. Are they DPSing in that downtime? Are they full on healing? Are the asking/ saying bigger is good? It will vary. If you take the mobs prior to first boss slow and it went well, then why would it not still matter at that point? You have two more camps to push through, so there's ample time to increase the pace.
And i'm a realist. There can be those who will rise, and there will be others who fall. But at the end of the day you're toying with someone else's experience, and from what I understand, potentially without their consent. I'm not saying to let someone live in mediocrity if that is where they dwell, but you're opting to just take the reigns of someone else's experience for what seems more like for yourself than them, rather than offering that guiding hand.
The quote before was purely metaphorical, not that I had assumed it's what you would say exactly. But what you would say bothers me. You thought they could handle it, but you say you just plunge head first without that gauging glance, so you only assumed. It may be splitting hairs but its assumptions like those that leads others, whom may not be as good-spirited as you, into a bad situation and taking it out on others. If they knew what you're saying now, would they be happy to know you just kinda winged it screaming Leeroy?
I don't believe in accepting the 1-2-3 turtle tank to keep doing his thing, but I don't think your methods are better. These experiences don't need to exist in extremes of either accepting the status quo or just blitzing it blind until something clicks.
Our personal experiences are what define our actions. This response leads me to explaining how I see this all.
Back around early-mid ARR I had joined the game, after a time between 1.xx and then, and I picked up MRD/WAR. My experiences with MMOs were slim-to-none, the concept of tank honestly was new-ish to me. I knew of the idea of tanks playing other games that weren't MMOs, but they can cast a different light. My time leveling MRD though was well enough, I was enjoying the idea of the tank; this was of course leveling to 50, so function was limited to just being tanky. Come to reaching 50 my world is opened to end game and all its quirks, among them being the mass pulls. Up until that point I was never pressed to mass pull or pull more than a camp at a time, it was never asked and I never considered it. And obviously would have been near impossible with what gear is available. So my FC mates at the time are explaining to me that this has become an almost necessary thing, because at the time the tomes farms were all about spamming the dungeons then, like Brayflox(Hard) and running them as fast as possible.
The idea of this was unsettling at first; I quite liked the careful and controlled style I was used to, so now this concept was like going from 0-60. Now being a fresh 50, gear wasn't just pouring from everywhere at that time and it was a little bit of work if you didn't really know what you were doing. But I gathered up what I could through MB and elsewhere and worked up the courage to press on into the big scary world of the Hard dungeons and whatnot. First run I did was with FC mates, and when I ran with them they were VERY pushy about me pulling large packs, not necessarily in a mean way, but more I got two experienced people telling to just do it, that they had it handled, and I honestly had no idea what was going on. Hindsight would tell me not to give into the peer-pressure, but I did.
The end result was obvious; my gear was nowhere near enough, I couldn't handle the damage and ended up in the dirt. What really nailed it in was the one on healer claimed she thought my gear was good enough. Being where she was, she should have easily been able to see I wasn't geared for heavy pulls, but she didn't look, she just assumed. The price of that was what confidence I had was near shattered and I was even more nervous than ever. I learned nothing from that other than my FC mates were butts. At some point after that I got desperate for better gear and decided to just throw myself into dungeon runs again, and it was fine until I came across one of those worst-case-scenario types of the most toxic and spiteful players, who was a BLM and tore me apart. I would get nervous pulling more than one camp, I would pull two, but it wasn't enough for them, they wanted more, so they would pull the camps themselves, and their gear was far superior, it was making the run an absolute nightmare for me. After that I just kinda gave up on WAR for the rest of ARR and all of HW while the tanking style of WAR was so aggressive. I considered the other tanks, but honestly those past experiences just kept me from working up any of that courage for the longest time.
tl;dr - Fresh 50 WAR, shit gear, pressured by FC mates of the time to mass pull. Got wiped, didn't learn a thing other than tanking was scary, later got shit on by BLM potato and got tanking PTSD. Still kinda working through it, tbh.
Long winded, but it's shown me that putting ALL the pressure on someone can end up really good, or really REALLY bad. And I feel this can be even more extreme when it's with someone you don't know, or maybe it's not as bad because there isn't any built trust to be completely shattered, idk. From that point, I've opted to take it slow and see how willing the one learning is to go once you give them a nudge, not a shove. Someone can push themselves on their own terms as hard as they see fit, but onto others, it's a game of tact.