My hospital corner skills are rusty as hell[1], but I note that that sort of thing is much easier if you have standing access to both sides of the bed. If you don't, then fitted sheets (preferably in a sensible colour) are a massive win.
[1] As evidenced a couple of weeks ago when I had reason to make the bed in an actual hospital. The slippy-slidey wipe-clean inflatable anti-pressure-sores mattress made it basically impossible to make the bed properly even if the sheet had been long enough, which it wasn't.