When is it worth switching to new versions of Python and when is it necessary?

Question

Python

Hello! There was a question on which the detailed answer did not find. When should you upgrade to a new version of Python? I recently started learning this programming language. Perhaps this is a stupid question.
Using the Ubuntu 16.04 kernel both in the OS and on the server, I am writing on 3.5.2. But there is already 3.6 and work is underway on other versions. I would like to know in detail when it is needed, and when can I sit on one version?
If there are good materials on this issue from whom? I will only be glad!
Thanks in advance!
UPD.
The question is rather from the point of view of learning the language and switching from one version to another.
Is it hard work or not? Is it possible to write safely on 3.5 then switch to 3.6, etc.

Answer 1

It depends on your temperament.
If you are chasing the latest trends in everything, you must, of course, move on.
If you are more conservative and don't care if you're in the mainstream, then you don't have to.
You have just read the best material on your subject.
UPD.
The versions are 100% compatible from the bottom up . You can calmly.

Answer 2

Is it possible to write safely on 3.5 then switch to 3.6, etc.

Yes, the 3.x branch is backwards compatible (by 99.9%), although some people slaughter old versions, which is generally not scary, and sometimes justified.
PS: I'm already on 3.7 recently...

Answer 3

Usually they are guided by the libraries used. Suppose if the library you need does not support the newest version of python, then you do not need to update.
In general, they are updated if there is something important in the update. For example, about a year or two ago, the implementation of dict was changed and now dict uses less memory and preserves the order of elements.

Answer 4

I try to read WHAT'S NEW for new versions and if I really like something, then I go.