I gotcha, so aiming to "build up" cards from Capital One or Chase isn't very practical if you don't really use the card much after I stop using it post APR free period. Well I opened discover Savor One (free period, nice bonus) and got approved with a CL of 5K. Going to use it to cover expenses that Discover can't until my Match period is over (June 2019) to maximize the return. So far its around 300 bucks. Once that's over I'll use Savor One as my primary card until the end of the year.
Discover and AMEX will tolerate low usage of high limits. If I remember correctly, Chase decreases tend to be related to weird usage rather than low usage.
But you're right to be concerned as some banks will decrease limits. Synchrony, Bank of America, and Barclays come to mind. Capital One will decrease 5-digit limits to 10k when usage is very low.
If you want to get limits just because you can, Discover and AMEX are the safest. For most banks, you'll want to land on a limit that you can justify with your spending.