Partitioning for Linux Installation

"(I forgot to mention that I have a ntfs partition for saving all my current Linux Iso Images.)"

This not about partitioning a hard drive.

 Linux is very well streamlined OS and it can reside in only 100GB.

I have a SATA disk of 320GB and it has 3 Linux distributions and NO Windows. 

I used to dual boot with Windows and certainly NOT for about 25  years.

Linux has enormous (60,000) packages and I decided to pick and choose with about 1500 to 2500 packages in Debian and Ubuntu.

I did follow my standard old method and I realized I need to increase the var partition for stability.

For Linux installation one /root partition is good enough but for stability one need at least 5 to 7 partitions.
If one ignore the modern EFI boot partition of about 528MB, the partitions I use are
/boot partition of 1GB.
/root partition about 30 to 40GB.
/var partition about 20GB
I have additional 40GB left.
/ home partition get 28GB
/tmp of 2GB
 

That is my global plan and if I have any additional space say another 100GB I will allocate that to my home partition.
There are other partition in use when the computer is shared.
That include
/srv for shared services
/srv/local
/opt is similar to temporary but more organized.
 

That's about all.

In addition one need SWAP partition of Twice the RAM.

I use at least 3 SWAP partition in between the working distributions.
 

The SWAP partition can be formatted without loosing DATA.