Before you decide on partitioning schemes it might help to actually understand the reasons for splitting various parts of the linux.

Firstly multiple partitions are 'safer' since if one filesystem is damaged, the others should be alright. This won't save you from a disk failure. Backups would, as might the parity scheme in your raid level.

Secondly it was a way to use multiple drives of different styles before LVM - this is moot for you

Source - Linux Installation and getting started

In short, the multi partition scheme is sort of a relic of older times, continued for legacy reasons. If you need to ask why, you're better off with a single partition.

In the modern context the smart partitioning method would be to use a single large partition (and a second one, optionally for swap, swap files would be an option). Use LVM so you can add disks if you can if you think you may need to add space. A single large partition means things will handle themselves as long as there's enough space, and you can backup /etc/ /user/local and /home, and use that and a list of installed packages should a bare metal recovery be needed.