Android free space decreasing Why are apps or cache constantly bloating in space in my android 5.1.1 device?

Every time I update &amp; use an app it bloats especially if it connects to internet.

I have to free cache every 4 months after which free space is around 1.5 GB &amp; then after 4 months it decreases to around 400  MB.
As every time you use any app, their is some caches for each sessions which is saved by app in device memory like if you are using Instagram it stores some of your starting posts in your device memory as caches for offline view. So as you clear your cache every time, device clear all the temporarily saved data and when you starts again using that app, it again saves some cache for your easy handling of app in offline view. So that's why your memory is decreasing