My guess is........unsprung weight beyond what the shocks are spec for is a huge factor in how long a shock lasts.

So, if you put on heavy tires (LT, for example, which are usually 10-15 lbs heavier than stock tire) on stock shocks, then expect its lifetime will be shorten. The same goes for aftermarket shocks.

In general, from my understanding, a mono-tube shock should easily outlast twin-tube shock. Better heat dissipation.

But again, if you “over-cook” it like you said with heavier than spec tire, then expect all shocks to fail...maybe mono-tubes will last longer when pushed due to better heat dissipation?

For example, Toyota had to re-tune their FOX suspension on the 2020 Tacoma TRD PRO because the 2020 Tacoma rims are each 4.8 lbs lighter. Imagine that...4.8 lbs difference (per rim) and Toyota had to re-turn the whole suspension.

Or in past 4runner models, there were different stock shocks depending on RIM SIZE!!

Or take the Edmunds’ comparo of Tacoma vs. Nissan vs. Ridgeline. The Tacoma’s and Nissan truck REAR shocks were leaking over washboards. The Tacoma’s were Bilstein’s mono-tubes. The front shocks on these trucks were OK i think and Ridgeline did fine. It is all about UN-sprung weight. Those rear heavy axles on these trucks put a lot of stress on any shocks, whether it be mono-tubes or twin-tubes. (Ridgeline escape unharmed because it has IFS and IRS.)

I don’t know about aftermarket stuff, but i am pretty sure that they are under the same limitations. These aftermarket shocks MAY have a wider limits but that is probably why you have worst ride.

Between aftermarket mono-tube vs. twin-tube, if everything else being equal, then mono-tube is the way to go.

But, if you want your shocks to last, IMHO, then be careful with unsprung weight. And this is why on my GX with its fancy ($$$$) electronic shocks, i am sticking with tires very close to stock tire’s weight.