Honestly, I’d apply this to any bank. I wouldn’t feel comfortable holding more than the FSCS maximum amount in any account, nor would I feel safe with 100% of my money in any single banking group. It doesn’t matter how much I trust a bank, I’d still like that protection from any issues, downtime with card networks and an easy exit if they decide to stop serving me as a customer for any reason.
On a similar topic, @hugo shared a concept for Monzo advising users of this very limit.
https://community.monzo.com/t/fscs-protection-ethics/7564/4?u=richardr