Don't know what the policies are for R-day, but not passing the APFT during CBT is not normally grounds for separation as I understand it. There are very specific policies around this. (white book?) I know it takes multiple fails during the AY.
DS and friends has had to help company & teammates with this on multiple occasions, even as a plebe. Some of them are regulars... just skirting disaster, then getting back in bad standing. The one exception was his plebe assigned as team leader, he went from failing in CBT to a B on his retake. His main issue was learning how to pace himself on the run.
The unfortunate thing is that many of the cadets DS helps were recruited for various reasons, and most likely would not have made it in otherwise just based on CFA alone. IE: they did not just fall out of shape. So this is not pleasant duty for cadets that got in without a hook.
Decent kids most, but some are living daddy's dream and not theirs! There are a very few he helps that are challenged by body shape but otherwise are totally squared away and fight very hard to improve and not drag the company/team down.
What I tell candidates who ask what the cutoff is on the CFA is that they don't want to go there.... the only thing worse than not getting in due to CFA is to get in and not be able to cope with the physical aspect of CBT, APFT, and later training.