Again you missed the point, if one deliberately set up a laser system to do cluster damage, it is entirely possible. If you can do it for an autocannon, you can do it for a laser. Increasing the time between pulses is just as possible as factoring in the reload time of a shell. The electronics makes it so you randomly hit the target per shot, so that level of drift is there, especially if the heat is altering the focusing lens. So, it is entirely possible if deliberately set up to do so. That's all I was saying.
Ah, but i'm not doing it based on what i see being deliberate but simply something that follows from function and its limitations, combined with game balance and function. EDIT In case of ACs, how i feel they should function, and how that would allow compressing and adding to the game's weapon variety at once.
So, game balance and function first:
-Autocannons should feel distinct from PPCs in the "big gun" role while offering competitive damage and range. Simplest solution, they spread their damage a bit instead of focusing it on one place (for contrast, missiles spread far more and deal less damage per shot, distinct enough), both to keep them distinct and prevent them from being overpowered.
-Likewise, lasers, being direct fire weapons even if they aren't "big guns", should feel distinct, thus they gain increased accuracy but short duration pulse keeps them hitting only single points (again, missiles tend to dominate multi-hit role at multiple range bands).
-Plasma weapons' unique catch is their heat generation in the target while requiring (non-explosive) ammo despite being energy weapons
-Gauss weapons have extreme range at the expense of the weapon being explosive instead of its ammo.
Then, some basic idea why this is so (but not quite actual fluff for the weapons):
-PPCs fire bolts of particles at target at very high speed, this accounts for single point damage.
-Autocannons fire a burst of chemically propelled shells, given all the limitations this implies, they spread around though since the bursts are relatively fast, there is only little spread.
-Lasers are lightspeed weapons, thus they have excellent accuracy, accounting for single point damage and to-hit modifier.
-Plasma weapons are similar to PPCs in function but fire different kind of particles and use ammo.
-Gauss weapons fire hypervelocity slugs requiring their capacitors to be extremely high powered, and cannot be armored properly without excessive weight.
(Actual fluff could be more like "modern laser combines previous ER, heavy and pulse technologies".)
Short beam duration is because i feel that is both realistic, functional, and "looks nice".
Long duration beams are a bit silly IMO for several reasons: they're potentially dangerous to wrong people (seen people manage to damage their entire own team with a single Clan Large Laser beam in MechWarrior Online), it is better to dump less energy quickly to where you aim it than waste energy spreading it around, heat should be more manageable with shorter duration system, and long duration beams just look weird as weapons for universe with somewhat hard scifi aesthetic. While you have been suggesting a pulse laser, i regard pulse and beam lasers largely identical in function in practice, with minor visual difference.
EDIT And increasing time between pulses is equally weird. Extremely risky too, if the target manages to run behind cover or something. I tend to imagine ACs firing one short burst per round, a burst that scatters, not something that fires for long time and scatters because of that.
There's also that i don't see much need for another cluster weapon in the standard, relatively simple weapon set. A weapon set, that i'd prefer to be in size somewhere between current Introductory and Tournament Legal (circa 3075) weapon sets, leaning toward the former.
I will admit that looking at my "big gun" options, there are more point damage weapons than otherwise. As such turning one more of them into cluster weapon could be an option, even though i don't see much need for that (i do kinda intend to have more weapon than needed after all anyway), and this could be an opening for non-cluster missile weapon. But i disagree with the choice being the lasers, or a laser variant.
That said... as i've been typing this, i recalled that i have drawn some inspiration during my prototyping from an old PC mecha game called Titans of Steel (which may be based on BattleTech). Most of those ideas were cut, with exception of laser accuracy which partially owes it to TOS lasers, but larger reason was that i compressed multiple laser types to single laser type. TOS turned lasers and pulse laser (just one type) around in that lasers gained accuracy bonus and pulse laser didn't. Strictly speaking those might have functioned as "ignore enemy movement modifier" rather than having accuracy bonus per se. Incidentally, this might be actually be better, more balanced bonus than straight up accuracy bonus, any thoughts?
Anyway, there could be perhaps place for another laser type in a standard set rather than just placing those into advanced/experimental category. Suppose there is a single additional laser, with single size only, that takes the place "Pulse Laser".
If it were to be a "cluster laser", it should still be somewhat distinct from autocannons (very few clusters, high damage, medium to long range), SRMs (low damage, many clusters, short to medium range) and LRMs (few clusters, low to medium damage, long to extreme range). Having a pulse laser fire many clusters would step into SRM toes easily. Plus a laser that "appears", even if by design, to be inaccurate looks even sillier than long duration beam (pulsed or not).
It could perhaps replace SRMs, with SRMs being turned to high-power short range non-cluster missiles (eg SRM-6 would become actually six different launchers, each firing short-range Thunderbolt-style missile). This would look damn weird though. Even Fallout Gatling laser, as stupid as it was, was relatively accurate, to the point it was arguably way too good thanks to plentiful ammo...
Also need some basic reason why it functions as it does, and then some kind of idea as to what its actual fluff would be (provided weapons are given actual fluff, as i noted before, sometimes it might better not to have that).