I'm slowly coming around to the idea that I don't need to fire all 7 hard points at the same time, constantly - the huge beams on their own do a lot of damage in most cases already, so the rest is more of a bonus.
I think that's one of the main differences between PvP and PvE.
For PvP, it's all about the "devastating first-strike" and (usually) your only goal is to explode somebody.
When you run out of ammo' you synth' more or go back to a station and re-arm so you can do it again, and again, and again, and again....
For PvE, you're likely to have more diverse goals and so prolonged combat-effectiveness becomes important.
It's a PITA having something like a Corvette, schlepping out to a CZ or whatever, and being absolutely devastating for 10 minutes and then needing to synth' reloads or go home to re-arm.
C4 Efficient Beams, on a Corvette,
will easily destroy 80% of the ships in the game by themselves - without using any ammunition at all.
You can sit in a CZ or RES perpetually, destroying ships, and never need to use an additional weapon if you don't want to.
Beyond that, it's all about optimising your efficiency.
Put MC's, rails, frags, PAs or cannons in some of the other slots, in a 2nd fire-group, and you can bring them on-line to give tough ships a good pasting and then you can switch back to the lasers and conserve all your other ammo until you need it again.
Also, to digress slightly, one of the reasons I prefer rails to PAs is that they make it easy to avoid squandering ammo.
With PAs it's easy to just keep plugging away with them and not hit much.
With Rails, the "spin up time" means you get a couple of seconds to think "am I still on target?" and take your finger off the trigger if you think you're going to miss.