I was approved for SSDI in August. Prior to that I'd been IP for less than 24 hours in Nov. '18. Before that I'd been IP in 1987 and in 1995. Recent IP doesn't determine eligibility. For example we have a serious shortage of beds here (which I'll bet is common in many locations). People are discouraged from going IP for that reason. So IP isn't necessarily an indicator of how well/unwell someone is.