It depends. If you have £100 in one bank, it's easy. With £1000000 in several banks, not so easy, especially if tied up in fixed term accounts, or is not in a high street bank, or whatever.
Most people I'd guess would be somewhere in between...
It's also highly risky if it's in cash. What will you do with it? Pay it into the bank across the road? Then there's no point, as customers of the other bank will be transferring their money to your bank...