Hey @MightyWolf.
I just completed the octopus challenge.
Well, it was a little hard but I did it in the end.
Now about the rewards part, not bad although I would like to get more stickers in order to unlock more boosters.

Ca 191

The map looks so pretty for the Bonus Run @MightyWolf! 

This was also my first time to have a chance at the Octopus/Cookie/Jam Challenge and I am regretfully failing. I believe that there is another Octopus level waiting for me next or the one after, but that would only take me halfway. I think much depends on where you are at on your map when the contest begins (mine was right after the Odus pumpkin challenge as well). For me, I had several levels to complete before I even hit my first Octopus level. 

I think my fastest pace is usually finishing an episode within a few days, typically closer to a week. Not going to lie, I don't rush. I got Odus Pumpkin within the first day but I spent boosters. I don't usually use boosters for star chasers unless it's a hard level and I would normally look at using a lollipop anyway. Like @caambuj said, however, if you don't use them you don't care as much about winning them--which is what I assumed the reward would be with the Octopus challenge.

What's the reward for Bonus Run? 

I really can't wait to try this bonus run challenge too.

First of all, I' m glad that @MightyWolf agreed with my comment. 
It's true that these challenges must give more rewards and especially more stickers for the outfits and characters that we don't have yet.
I hope that team will fix this soon.

And also thanks @caambuj for the kind comment.
Firstly, I would like to say that I'm not actually a fighter but I'm just a girl who has passion for Candy Crush Games so much and who gives all its best to complete those challenges.
Sometimes I win and sometimes no.

Plus there are more players here which are better than me in this game (and I mean the ones who started to play CCFS from its launch day, the ones who have or even try to get all the characters and their costumes etc) .
And yes, I' m one from the lucky ones who can get those events and I really wish and the other players who don't have those events yet to join them in the future.

And about boosters, I'm trying all my best to collect and use them only in hard levels.
And thanks for the advice too. Don't worry. I would never reinstall this game since I like it so much.

P.S: From your screenshot @MightyWolf , I noticed that Bonus Run Challenge's background looked like Dreamworld from Candy Crush Saga.
I don't really know if I'm the only who noticed that but I really liked it!