I will with you halfway through with this, here is how I view it.
If you have little experience with telling between safe sources and sketchy, then yes, stick with the defualt.
If ypuu know about some safe appstores or repositories then that's when you could say you are qualified to make thes decisions. Like I know Fdroid is safer and better than the defialt on everyway for the users best interest, but if you dont know your sources then you should not sidelode untill you do know how to make good decisions.