I think that having miles in multiple programs is a good idea if you earn enough to have a meaningful number in my than one program.
Unfortunately my 2 largest balances are AS (from flying, including partners) and AA (from credit cards), and most of AS' best partners are OW so there's a lot of overlap there.
I'm (at least) hoping to turn my Chase pts into an SQ Suites redemption eventually. Also I hear that SQ redemtptions are coming to AS some time in early 2042 so my retirement plans are looking solid.