Backup app on Android a good thing?

Is it really necessary or at least a good idea to use an app to backup data on an Android phone (contacts, etc.)? I have been using Avast Mobile Backup and I keep hitting my max storage limit on Google Drive but I don't want to pay for more storage.

from Android Forums at AndroidCentral.com - Ask a Question //forums.androidcentral.com/showthread.php?t=765738&goto=newpost
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