What is the best practice to upgrade/patch the RHEL Servers?

Dears,

I have a number of questions regarding upgrading/patching RHEL version (packages). I am using RHEL 7.X.

In general, what is the best practice duration policy to upgrade/patch Major RHEL version on a year? (i.e. from 7.3 to 7.4) And what is the minimum number of times to do the upgrade/patching. Moreover, when it necessary to upgrade just some packages, and when we need to upgrade the whole packages?

Regards.