I'm very - very sad

Twice a week, that's too often, waste of a LOT of HDD space and also, if you encounter problems that started with something you did like, a month ago, you will need older restore points to fix it, and you won't find any Unless you increased the max ammount of HDD the restore points can occupy... up to 10 %.

That'd work, and ofc in the moment before installing something vital on the PC, or important (in most cases it's automatic, when it's about Windows).

Of course, you just have to leave/have some free space left on the HDD when you install the 1rst OS. If you already made a partition (where if you didn't do any, it automatically takes all the HDD), then you'll have to uninstall that, then create the partitions, split into 2, 3 parts of the size you want, then installing each OS in each partition in the same way you install it with no partitions. Instead of selecting the empty space, you select a partition.