If you spend every day between submission and the viva doing some effective viva prep, then you’ll be in a great position for the viva. If you do nothing between submission and the viva, you probably won’t be in a great position for the viva.
Do some viva prep regularly on the lead up to the viva. But if, say, on a Bank Holiday, you take a day off? You’ll be fine. If there’s no bank holiday in the period leading up to your viva, still take a few days off. Well-placed breaks are just as important as the hard work you put in towards a goal.