I recommend to post every day, however, you can post once per week and still receive upvotes but it will be unlikely as people will get less curation for it.
Remember: The better the impression of your article is and the newer it is, the more likely you will receive upvotes.
And besides that you are correct: Your Steem Power is related to the value of Steem.
I remember when I had 20K Steem Power (delegation) and a 100% upvote was almost worth $20 here. Good times!
Unfortunately posting more than 2-3 times week is an absolute maximum for me if I want to continue with music videos. In 2017 I spent about 1000 hours of shooting footage; that's half a full time job just to get footage not including travel time. Maybe it's time to do Cat, Dog or Ferret videos and cash in on the cute factor, lol.
It all depends on your priorities.
With Steemit I make more money than a good lawyer (depends on the market value of course) does from home without having to deal with customers & clients.
That is why Steemit receives the most time of my day.