@FirTree31 the easiest way is to move savings on payday. This is how DH and I work it.
I manage the money in our house.
So DH and I both get paid and tax credits also go into the joint account and all joint expenditure comes out of here, so literally all bills from mortgage to gym membership inc food and fuel.
I have a spreadsheet that tells me how much each bill is and totals it up (I work a month behind) I then remove that total from how much we get paid (salary so same every month) and look at what's left over, I transfer between £100 and £200 into our own accounts for own spending, so nights out with friends, buying ourselves new clothes, days out with dcs etc.
And the rest is put in joint savings. The reason I work a month behind is because food shop and fuel changes, this means that I look at what we spent in March at the end of April, take bills out, take personal spend out and save the rest. Its approximately £300-£500 a month.
But since lockdown that personal spend has been going into joint savings as we've not bought much so just used the joint account, think takeout when we can't be bothered to cook.
In usual times, I put £50 into my personal savings and dh puts whatever he wants into his. Also as I mentioned up thread, he also had an add on with his bank account which rounds his transactions to the nearest £1 and saves the difference.
We've always tried to maintain a years salary in savings across the 3 accounts, however, new car and having children have eaten away at it.
I think it's down to money management skills. Although I'm a spender and dh is a saver, he has no concept of actually controlling his money, which led to some fun conversations when we first started renting.