Being very much aware of the 2nd gear problem I was very careful shifting my 86 FJ .
I did miss a shift once or twice at the end of a ride at low rpms on my way home hungry and tired.
keep in mind that at the time I weighed in at 385 lbs, and would upon occasion ride 2 up with my wife 120. lbs.
So my 2nd gear issue started at redline and slowly crept down the rpm range to 8000 rpms . most of the time it would hold on a straight level road but as soon as a vertical climb under power it would pop.
So I lost 100 lbs with a diet and was able to keep the pop at 8k for a while until it started to get worse again.
It made its way to 6k rpm and at this point it was too annoying to enjoy riding it with any hills.
I had RPM put a new trans with all gears undercut and the beefy shift forks and detent kit.

Now this is my opinion. Derived from mine and others experiences of the fj . ..........
ALL FJ years have the potential for the 2nd gear problem, the stronger forks of the 89+ years will delay the problem.
It really just depends on how much weight you carry and how steep the hill or high load.
If you baby the engine in 2nd gear you will most likely never have the problem.
Spirited riders and mountain pass thrashers will find themselves splitting the cases one day.
MarkO