I'm not going to recommend this, but just as a matter of principle on my rider bikes with reverse threaded fixed cups, I remove the fixed cup everytime I do bottom bracket maintenance, which is at least annually. My theory is that if you do this periodically, it never gets tightened to the point that it becomes an issue. The bikes on which I follow this regimen, the fixed cups always come off w/out any drama at all, only takes a few moments. The consolation prize for this (tiny, tiny) bit of extra effort is it is easier to clean the cup and I get to take a better look/see, clean/regrease threads, etc.

Just off the top of my head, it is probably about 2-3k miles between this type of maintenance.

I've used the Sheldon tool for years. Again, on my bikes following a periodic maintenance schedule, it isn't difficult at all. But on other bikes, while it has yet to fail me, it has been a close run of things a few times.

Another thing to consider is that your riding style is also going to influence how tight the fixed cup becomes. Remember all that stuff about for every action there is equal/opposite reaction? That means that if you are a pedal masher, get out of the saddle on hills, etc, your fixed cup is going to end up tighter than if you are more of a spinner. I'm much more of the latter, which helps keeps the maintenance above a bit of an easier task.

YMMV