I believe from the DPs that once you have the permanent Coastal One card, you are no longer able to load at the SCO. That appears to be only available using the temporary card purchased at WM. I do almost all of my loading at the cashier without issue, but have used the CSC as well.
I do my withdrawals after a retail purchase at WM. You can do it either at SCO or the cashier using your permanent Costal One card or the One app. While I do only $20 at a time, I believe you are given at the SCO a choice of up to $80 in $20 increments. I suspect if you wanted to pull $100 at the cashier, you could, but again, think of eyes on your account, and try to minimize activity that would lead to same.
I have a DD account with Coastal One, so the account gets $500/month from my IRA due to a required RMD. That usually goes into the savings account, but if I need cash, I can get it from either the cashier or the SCO line. I drop using GCs around $2-600/month but do no BPs. However, Coastal One is a checking account, so there would be no reason not to use it as such, if you wished. This would be especially true if you had some steady source of cash inflow, for example from employment or pension account.
It is my opinion, (and only that
) that the more you mix up sources of cash inflows, especially if they are < 4 digits in amount, the less likely the bank will care. The numbers will be too small and too diverse for anyone to bother with unless there is some egregious event which casts human eyes on it.
This has worked well for me using One, Go, BB and Serve for the past almost 10 years. But everyone has their own method, and I don't discount those either.
Adding one other thing. If you have the One Pay Cash+ account, the saving account pays its very competitive interest daily, which effectively does increase the APR rate (versus other banks who pay either weekly or much more commonly, monthly.)