The simple answer is that if you are voting a lot already on your own, then one might not need to follow a curation trail. BUT if you employ a voting strategy, then your vote and curation rewards are consistent.
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Bandwith, yes. That is the case for everyone. However if one takes a break from steemit, then one will be missing out on the votes. You earn steem power from curation rewards. One can also lease SP, steem power, from places like minnowbooster.
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Personally, my greatest reward in Auto Voting, is that I will always be able to vote on creators I like. I use SteemD or steemdb to see what I voted on recently so I can see what I voted on, and not miss an article or post. Hope that helps.