I like the hardcore aspect of the current streak system and find it extremely motivating. That said, I do worry about exceptional situations such as if I'm extremely ill or unable to find internet while travelling through developing countries.

I would find it disheartening if I lost a streak due to these circumstances. Perhaps there is a middle ground, where the punishment for missing a day is more extreme than losing a day but less extreme than losing the whole streak. Say losing half your streak or losing a month, or anything that feels quite harsh without disrupting massive streaks due to unfortunate situations.

Thanks Marc, I'll give it a read.

Hmm it's a tough one, as an advertiser I personally wouldn't be offended by that design if the advertised product has nothing to do with job boards and isn't a meaningful competitor.

I don't know much about your user base but as a user I may have the opposite problem, where I may be slightly annoyed with the ad if it isn't related to job searches.

If you're confident your users will remain unperturbed I'd probably put it in and wait to see if any of your advertisers complain, and remove the advertisement swiftly if you get complaints from your big job board advertisers.