As humbling as I find mental calculation to be I often wonder whether the struggle improves my general clarity of thought. I am not sure whether this is emotional, becoming adapted to the frustration of thinking at your limit or if it is an intellectual skill, learning to think clearly. Testing for these kind of things hasn’t been shown to have significant carry over but it seems to me that daily thinking practice does sharpen the axe.
I was just playing with exponents to 10 of single digits and solving them mentally with different obvious strategies in my head. Occasionally hitting points where I overwhelmed short term memory or my rational circuits.
I know I can grease the groove,. Improve the circuits through regular use, employ better strategies, and improve my familiarity with the content.
I think though, that there is an additional element. Becoming accustomed to mental failure/ambiguity and learning to work through it effectively/efficiently.
I wish I had more natural talent and youth. It would be very nice to have fast, broad success instead of small, cumulative improvement. That said, the process itself seems to have qualitative benefits. Sample size of one.