If you love some variety, you will love this game. 3 in 1 means to mix three different scoring formats in one round of golf. You simply change the format every six holes. You can use whatever kind of formats you prefer. For example:
Holes 1-6, battle golf (see day 10)
Holes 7-12, bingo bango bongo (see day 15)
Holes 13-18, worse ball (see day 2)
You can use all the formats I provide under the go play sections of each day or use whatever rules you like. Just make sure that all three formats are chosen before the round so that there is no confusion or discussion later on. Depending on the formats you play with an overall score or give points for each six hole match.
I think it is great to add some elements of luck to the last six holes. You get some ideas in this book, e.g. the Viva Las Vegas of day 25. This way your round will get even more exciting towards the end. I like 3 in 1 a lot because it is really like three small matches one after the other.
It somehow gives you the mindset that you can still win, even if you messed up the first six holes. Just because each format seems like a fresh new start. That mindset is also useful for a normal round of golf. If you approach every hole with a fresh mind as if you were going to the first tee, every time you probably perform better. Of course that is easier said than done most of the time. With 3 in 1 you have a good and fun way to condition your mind this way.
Play three different formats during one round of golf.
Split it up by six holes at a time (1-6, 7-12 and 13-18).