Unity 5 Each Platform Support

I have one question regarding multiple platform support in unity 5.
I notice that there is different platform build, I need to download to provide support for that platform.

Even iOS build support is more than 1 GB size. So my question is, If I have downloaded iOS platform support for unity 5.2.0 then whether I need to download same iOS platform support for Unity 5.3.0.
Whether I need to again download more than 1 GB data for new installed unity version?

I am using Unity Download Assistant for this purpose.

Please give me your suggestion in this.

As Graphics_Dev said, it’s always a good idea to use the latest stable versions, unless there is a good reason not too (i.e. towards the end of development cycle and new versions may introduce some instability).

To your question specifically though, you should always make sure your versions match up. Don’t use something intended for version 5.3.0 if you’re on 5.2.0 and visa versa.