I've switched to using minnowbooster as my only pay to play upvote service and I only use it to upvote 4-6 day old posts. I do this for two reasons.

First to get a little positive ROI while coverting SBD to Steem Power.

Second, to give a reward to my upvoters with some exter curation rewards. I try to make sure to minnow booster posts that have been upvoted by both @qurator and @minnowsupport .

I would prefer seeing Minnow Booster keep the 5SBD a day/15 SBD a week limit so the vote power climbs.