My advice would be to buy a monthly ticket to your desired areas and then look into getting yearly passes. With corona these days not everyone is expected to be in the office every day.
0. Getting Halbtax is a very reasonable thing to do, if you are going to stay for a couple of weeks at least. Best value when used annually.
1. For several (more than 2) trips in a 24 hours span getting a 24H ticket makes a lot of sense: it costs as much as 2 separate trips in most cases. It lasts 24 hours, so for a ticket bought at noon you can use it for your afternoon and evening trips on one day and even the whole next morning.
2. Another option for complex or unpredictable trips is a check-in ticket with ZVV, SBB or alternative apps, which is a good choice with only one unfortunate flaw: it always cuts at 5AM, so 24 hours ticket is sometimes more cost efficient.
3. Adliswil is Zone 150, Horgen is Zone 151. Full list (and maps) can be found here:
4. There is also Albis 24H Ticket, which sometimes is the best option moving between Zurich and Horgen, when you happen to have some other business in Dietikon, Uetliberg or Birmensdorf.