A (bad ?) way of tanking...

[Degaulace]

say you have a 3 pull of mobs. 2 casters 1 melee. in a Caster Melee Caster formation. If the 2 casters are spread out to far my aoe will not hit them both. So i will pull the pack back and try to "Range" the casters in the pull to group them up closer so that my aoe hits all 3 mobs at once.

That's quite logical, but say your two dps are ranged ones. When everyone take care about the melee mob, the casters mobs attack the tank. But as the tank can't attack the casters mobs, the casters mobs may switch target to one of the dps (or the healer). In that case, the caster mobs are forced to come closer from the group, for them to be able to hit your range teammates. Therefore, no need to run back and forth to pack the mobs, as they'll end up packed anyway.
In fact, everything depend on the situation.
Besides, there's not really a bunch of caster mobs in lv <47 dungeons...

pre-50 dungeons are learning dungeons. maybe that's why you get newbs. Just a guess..

That's precisely what I said, even if I wouldn't say these dungeons are "learning" ones : why would they be ? They're neither easy nor difficult, they're just adjusted for low level characters, the same hi lv dungeons are adjusted for hi lv characters.
Every dungeon became easier when your lv is synch, and the HM/EX/endgame dungeons will be very easier once the max lv is increased.
For the rest, it's only a matter of practising and learning of different patterns...

Also, lots of "lv50 tanks" just burned through FATES if it's not their 1st job, so (sorry to say that) they suck horribly at maintaining hate. That's why they do lowbies to train and learn what they skipped previously.

Why "sorry to say that" ? Because you're a tank yourself and you're afraid to hurt your colleagues ?
We ALL know it's true, and not only for tanks, not only for secondary classes. Many players rush to lv 50 in main class without even do a single story quest.
But it's another debate...

No. In real world, if dps go crazy, ESPECIALLY summoners, it always end bad. Let's take an example which happened like 20 mins before I write this : WP run, smn/blm compo. No matter how well I did on my packs, I couldn't keep hate on the 3 packs bunch I usually go through until I spammed overpower preemptively. And he was doing nothing but his DoTs. Just releasing hell a bit too soon for my positioning.

As I said, many tanks don't understand their role is to do everything is needed to keep hate on them. If that means Overpower spam (in your case), so be it : spam it.
As for me, I almost ALWAYS cast my three dots then expand them to the mobs around as soon as possible. And when the tank do his job, I NEVER get the hate, even if he's not lv synch. Absolutely NEVER.
If the only way for the tank to keep the hate is spamming his agro skills like crazy, whatever the reason (too much bursting dps, for instance), then he have to do it. Especially for the WAR, who can easily control a whole bunch with Overpower. Period.

Ten seconds, though excessive, isn't that wrong. 10 seconds is nothing, compared to a wipe if your tank NEEDS that time to maintain a good hate build.

If he needs THAT time, he plays real bad and he needs to learn. As a dps, give in to this playing is stupid, as it will validate the tank's bad gameplay.

so you'll get 35 potency hate every 30 seconds without doing anything. of course you're going to put other DoTs above it, and a lot of other stuff like ruin when you have nothing left to do. This can totally overdamage a monster if the tank is spreading the hate build (if not, you'll take hate even faster). so it's less effective on hit but totally bullshitting the threat build if done wrong

The ONLY issue I ever encountered with placing my three dots (with or without expanding), is me suddenly getting the hate of mobs I just never hit and which are not affected by my expanded dots (in a situation where the tank do his job well, of course).
Damage is not the only parameter in hate. The dps, especially SMN and BLM, are über strong and deal monstruous damages, when compared to what can do a tank.
But a tank possesses damaging skills that generates more hate than other equal-damaging skills.
Even if a dps burst like crazy, the tank should be able to keep hate.
Even if it means spamming skills like Overpower, yes.