So just some general theory talk since I don't think it'll be covered by anyone else:
1)
Why the big push on Cheeky?
When I play scum I like to play town leader. Contrary to popular belief you do not generally get townpoints by playing town leader as scum, you actually expend them: but the flipside is you get an immense level of control over the gamestate and can often just lynch your threats instead of nightkilling them. As Cheeky was vying with me for the position of town leader she was the number one slot I was interested in reading and there were a lot of ways she was doing it that felt disingenuous and she was buckling down for a fight and given a lot of her tells indicated that she was a lot more experienced than she claimed to be, I didn't think she'd ever get lynched if I didn't lynch her. So I went after her really hard. I was pretty sure she was scum, but a lot of the fervor was brought about by thinking that she was just far more of a threat than anyone else and even if town I wasn't super happy about the direction that she was going so I sort of wanted her out of the way. That was far more of an afterthought to the scumread I had on her and don't misrepresent it: but it was there.
2)
What exactly is the purpose of the claim?
If she is in fact a doctor, there is guaranteed to be neither another doctor nor a bulletproof nor a jailkeeper in the setup. On top of that, if there's a cop it's reasonable that she exists, and if there's a tracker she is guaranteed to be town assuming no counterclaim. By doing the counterclaim, we can make her extremely likely to be town if uncced and obviously lynch her if she is counterclaimed. In doing so, we're also not putting our own major PRs at risk: in the newbie setup the 'true' powers are the Jailkeeper/Cop/Tracker to which the Doctor and BP are comparatively far weaker: it's worth pointing out that Doctor >>>>>> bulletproof, but it holds true and by not outing the specific PR we lose no information but deny scum information.
3) Why not have the jailkeeper claim?
Because they don't have to. There is guaranteed to be exactly 1 tracker/cop/jk in the setup. The jailkeeper's flip confirms Cheeky as scum and they can counterclaim whenever they want to score a free lynch on Cheeky. Scum are also incapable of claiming jailkeeper without immediately being CCed and creating a 1v1, which is generally super suboptimal for them. So the jailkeeper can wait till LyLO if they wish and then counterclaim and Cheeky is just as confirmed scum because there's no possibility of the counterclaim being fake unless her scumpartner opted to defend her: but that confirms BOTH scum as scum if we correctly read the real jailkeeper as town. So there's little to lose from delaying the claim, and as the Jailkeeper in a setup with no roleblocker is a very strong power role that constitutes the entirety of our non-scumhunting power, we don't want to have them claim and die early on.
2019 stats: Town WR 76.7%, overall WR 81.667%, 1 scum defeat involving a major mod error in lylo vs 8 scum wins.