We're not money savvy people particularly, however my girlfriend and I both have 3-4 bank accounts (UK based, it takes <1 hour to setup a brand new bank, from start to finish).
We have a couple of traditional banks, and then also some more modern "internet" only banking (great for travel with their zero conversion fees, and more granular tracking of spending).
This seems to be the norm between all my friends also.
I personally just don't see the point of having multiple banks manage my accounts. In the USA many of these banks require a minimum amount to avoid fees and since they can arbitrarily set those limits and they can change at any time I find that having multiple accounts ends up being a liability. On top of the non-existant interest why would I park $1000 in a bank account? Instead I can at least invest it in something. Heck even just adding that $1000 to my mortgage payment would be a vastly better investment.
Also UK, mostly because it's easy to get one account, fairly easy via your phone to get a joint.
I have 3 accounts, one for salary deposits, one for bills and one for spending so that I always know bills are covered every month without thinking about it and my "fun money" being pre-allocated each month helps me be mindful of my spending.
Since moving to that system I've been able to save significantly more each month.
Because banks can have IT outages, and you can have no access to your money until they get resolved. They also can go bust which means you can be waiting a long time for what's left of your money.
Well I use a credit card for almost all my purchases and I don't even need access to my bank to make my monthly payment. I wouldn't split my cash equally between two banks either. That seems silly. If for whatever reason my bank went bankrupt I'd simply open a new account and change my direct deposit at work. It's not really a show stopper. Plus there's federal insurance on all accounts up to 250k.
I think having a second bank for savings/emergency can make sense for a number of reasons (harder to conflate your money, accessible if the first has an issue, etc, better rates, etc).
I have an online centered account and a local one, they serve different purposes.
I think one big difference in the UK is instant payments, if you have money in the wrong account and need to move it you'll be able to do it within a few minutes. If that wasn't the case then it'd probably be a lot more stressful to have your money split up.
We're not money savvy people particularly, however my girlfriend and I both have 3-4 bank accounts (UK based, it takes <1 hour to setup a brand new bank, from start to finish).
We have a couple of traditional banks, and then also some more modern "internet" only banking (great for travel with their zero conversion fees, and more granular tracking of spending).
This seems to be the norm between all my friends also.