Most of the weaknesses have been discussed in prior threads. OA removes zinc. So galvanized parts don't do so hot. Most common example: spokes. On low end wheels (like Schwinn Varsities), I have accepted some zinc removal as part of the process. The alternative is to unlace and relace the wheel. I would do that on something special.

I keep recommending using it in really dilute concentrations, much lower than many people are using. I think it really reduces some of the issues others have. Do the math, I use 0.2%, thats 2 parts in one thousand parts. One gallon of water weighs 8.33 pounds. So in a five gallon bath, I only add one ounce of OA. That is not much for sure.

OA does not like grease, it tends to mess up the bath quite a bit. I find I get sludge from the grease.

Warmer works faster, and dissolves better.

Really best for stuff with significant issues. On small spots on frames, I tend to just use a rust converter paint, and touch it up (particularly in an area that is not too visible).

And of course, if the chrome is pitted, or worn away, it is gone. So after the rust is removed, you will have bare steel areas.