I was in Munich briefly two weeks ago and thought I'd pass along a tip to a new feature in the MVV app (Munich transit system/Münchner Verkehrs Verbund.) It's called MVVswipe and it avoids all worries about how many zones your trip might cross or whether to buy a day ticket. Very simple to use, which the general MVV ticketing site/app is not (too many options, and a requirement to understand the zone map in Munich so you know what ticket to buy.)
Download the MVV app before your trip. Set up a profile, including a payment method. Then wander to your transit stop, open the swipe feature and swipe right to start a journey. Your card will be charged 10 Euros. When you finish your trip, with however many transfers required, swipe left to stop the journey. If you forget to swipe at the end, you will get a reminder on your phone. Rinse, repeat all day. Overnight you will be refunded or charged for the difference, using the best price available for the rides you took. The app also retains a record of your swiped rides and amounts charged.
This worked flawlessly for me. I had sweated over the details of my transit trips in advance, trying to understand where I crossed zones and which ticket would be cheapest. This was a great solution. Of course, this requires phone service and willingness to attach a payment method to the app. And I think ApplePay is not supported, because I ended up using PayPal as my payment method which is never my first choice.
I recommend it.