I like the way the bus passes here work - they aren't for a specific amount of time, instead you load money onto them like a gift card.
We often buy passes like those when we're on vacation, but since we don't know the cities well we usually end up putting more money on the cards than we end up using so we don't have to stress about trying to figure out all the costs. On our last trip we give the cards to a local person, who is always delighted to get a few extra trips for free.
London Transport has this - the Oyster card, which gives a discount on buying a ticket; but if you have a contactless bank card you can use that instead, which is great if you're just visiting. I've got an Oyster card ,but had unused money sitting on it for months.