Is the data usage a trend in terms it is consistently being used every month or only for the first few months?

I know messaging apps such as LINE and WhatsApp take a lot of data especially if you automatically save media taken by your other friends especially if you are in a lot of groups.

When I was trying to find space for my 16Gb iPhone, I realised that WhatsApp and LINE both each took >1Gb of storage space thanks to all the media saved.