General TD Crank Limit Question

I am running a somewhat different TD jigger compared to most people on here who are more traditional in using what is proven to work. My jigger works very very well for what I need and using my android phone RPM Gauge app, it is usually running at 22/23k on the bench. My app might be inaccurate and the revs lower. Anyway I am not tach racing, or racing my planes, just flying them for sport fun and having a blast on the weekends. I am using standard Cox Glow head and 3 gaskets, 25% castor, 25% nitro, 50% methanol, 5 x 3 prop and I tend to needle back to about 20k before launch as this is plenty powerful for what Im doing.

My main question is based around stuff I have seen on other forums saying the TD cranks start breaking after 26K. I wondered what people here have experienced with their TD cranks. As I said, Im nowhere near that, but am interested as would like to get good life out of my cranks. I do polish my cranks with 400/600 grit before assembly and keep my piston well set, as its not hard to take the cylinder off to check the piston is set ok, and if not quite simple to take off the backplate and reset, and no gaskets!!! But I do use a little bit of Anaerobic Permatex on the crankcase and backplate mating surface. The other thing I was wondering is do the cases wear faster than the cranks. Like is it common for a crank to live in several crankcases over its time? I assumed the cranks would be harder than the case and the case would wear quite a bit quicker?

Not critical questions to my flying or use of my engines, as I only needle my jiggger to what is needed which at 20k seems below the stress points. The other great think is the TD is soooo light compared to my beloved surestart engines. Just questions out of pure interest as to what people have learnt and experienced about this over the years.

Yabbby