Great post @uwelang - it is a dangerous pond/lake/sea/ocean, depending upon perspective - I am sure you know of Zappo's and their online presence - it is a very different hat for a bank, user-generated content ... asking for trouble!
Engaging and relevant ... the two words which should define your presence. I used to tweak the characteristics slightly from FB to Twitter to Instagram etc such that you could measure the performance of each character. The whole objective is confluence and, as you quite rightly said, this takes time!
It can also take up a lot of one's day and guarding against that is equally important!
Namaste. Voted and followed as an Aspiring member should!