I do the same on credit card bills...have not paid interest on them since 1997. OK I did pay once because forgot to pay on time. Still not bad considering we have 3 active cards usually.
As for saving accounts and CD’s...have none. I am forced to buy hi-yield bond funds (risky risky) which are all in variable annuities. At least annuities are tax deferred for unlimited amounts.
Money I have outside checking is in a mutual fund the annually rebalances my holdings to maintain a certain ratio of bond value to stock. If I didn’t have that, I’d probably put everything into an S&P 500 index fund. Very low management fees and since mutual funds commonly measure their success against the S&P 500 with few regularly beating the fund’s rate of return, why not just lock into the standard others chase?