That's right; it does not matter how often you post (as long as it's once a week- but that restriction will be removed with automation) you still get the same value.

Currently we look at what % of updates received a full upvote over the past 28 days. You receive that % bonus to your upvote value. So the bonus would start small and build over time until you are receiving a full bonus. That will also be changed with automation, so we recommend reading our recent announcement:

https://steemit.com/busy/@steembasicincome/steem-basic-income-rshares-and-automation