Have a look at this flow chart...it's not one-size fits all, but it's a pretty sensible appoach to personal finance planning...
Having 9 accounts is mental... and are you aware that the 20k ISA allowance is
only once per year, meaning you can put another 20k into (say a very safe cash ISA) every year, tax free. So then you benefit even more from tax-free compound interest...?
A starting point for your financial planning journey in 8 steps, from the wiki for Reddit's /r/ukpersonalfinance!
ukpersonal.finance
For example I opened a Chip cash ISA in March this year, I put 20k straight into it, and as April is a new financial year, I banged another 20k in, for a total of 40k.
It's current balance is ~41k..
I've made a thousand pounds in tax free interest in 6 months from 40k, by literally doing nothing and watching the account grow.
By splitting your investments over many accounts, you're not getting the full benefit of compound interest on larger sums in fewer accounts.