When paying for Adult Brighton & Hove fares, in the city, whether it is cheaper to use tap-on-tap off (ToTo), is very complicated. Especially as the cost of the second and subsequent days 'ToTo' ticket is reduced, within that week.

If you are using short hop, or two stage fares, then using 'ToTo' is usually cheaper. If you are making more than two journeys in a day, then a daily App or Keycard day 'Saver' fare is cheaper. At four days, paying 8 x £3 fares on 'ToTo' is cheaper; but if you are making multiple jouneys, the price of the ToTo Saver, just saves a few pence, over using the app to buy one day Savers. However buying multi-day tickets on the app, should be cheaper still. If you are travelling 5 days a week, then a weekly Saver on the app or keycard, becomes cheaper than ToTo. As the weekly 'ToTo' price cap is now £28.70.
Monthly and longer tickets can offer better value for money. Looking at the 28 day ticket: if you use it 5 days week (£4.91 per day) you will save money; but if you only use it 4 days a week (no multple journeys), at £6.13 per day, it becomes slightly cheaper to buy two single £3 tickets a day, using ToTo!
The 90 day ticket becomes far better value for money. At £259.90, this works out at £4.04 per day (5 days a week), or £5.05 (4 days); cheaper than even a two-stage tickets. However this is a large sum of money to find, in one go. Phew!