Need to confirm something, if someone got a regular season bump, does it mean they will not receive recovery bumps again? If so, should I take them off the DL and play them then?

Yeah. If you've left a player on the 60 and you see more than one line that says "Injury Recovery", and now you see the most recent line says "Regular Season" again, it means they won't get any more injury recoveries. Might as well take them off the DL.

How does this strategy work? I am not clear on it. Should a player be left on DL beyond the recovery time for additional recovery or boost?

Yes, if you have 20/20 for training and medical. If you leave him there longer, he can end up with ratings higher than they were before the injury.

If a player gets a minor injury, place him on the 60 day DL for a steroid injection. Better the medical budget, better the roids.
Downside is you lose the player for the 60 days

Does the players age matter?
can this happen more than once in a career?

Age doesn’t matter and it can happen multiple times.

I'm gonna write this out, for a fuller explanation. Anyone disagrees, chime in.

Some of the injuries in HBD can be severe and career-altering. Some of them take more than one injury recovery bump to get the player back to pre-injury status. How your players recover from injury depends on your Medical budget.

Know how we usually ask, is it any good to have Advanced Scouting? That's because many of us choose to live without it and have decided we can play without the benefit it gives. Medical gives a clear benefit and tangible results. That's why I view the 60-Day DL as a FEATURE, not a BUG.

When you budget 20 mil medical you are signing up for your players to get the chance to get multiple injury recoveries as long as you leave them on the 60. Sometimes you need that for long term injuries. Where the Trick comes in is when you leave a player on the 60 after full recovery to see if he gets any more injury recoveries. And you're exploiting it when the player has a shorter term injury but you 60 him anyway just so you can do this.

Timing of the injury counts. Depending on where in the season calendar you are, the player might be out of luck. Also the type of injury can be of benefit. Rehabbing a pulled groin isn't going to help a pitcher get better.

It works with less than 20 medical; just not as well. I've had positive results with 10 medical teams. Replacement jobs of course - I always max my medical budget.

Are the "injury recovery" cycles typically the same length as the "regular season" cycles? Seems like the risk of leaving a guy on the 60-day beyond his injury is that he may never get the extra bump or it may take a long time.

Not sure about the length. I think they're the same, but I haven't actually documented it. And yes it's a risk all round. I just had an old SP who I left on the DL to try to get an extra bump. He got the first recovery, but didn't get a second, and because he's 38 years old, the regular season update was actually a decline from the injury recovery. Live and learn.

I have 19M in medical. Where can I realistically expect this player to be next season?

https://www.whatifsports.com/hbd/Pages/Popups/PlayerRatings.aspx?pid=5665521

Injured in his first start for me, game #4 of the season.

The hope here is that you are able to add him to the 60 Day DL next season, I'm not sure of the math but I think it will work out that way. Shoulder Aneurysm is a "good" injury for it to work. I'd expect him to be back to what he was at minimum, and more than likely plus 1-3 ratings points

... Except he's going to be 39 next season. TBH he got off kind of lucky with this aneurysm, it mostly took off his Velocity rating and I've seen them be much worse. Thing is that I'd expect him to be around where he is right now at the start of next season had he not gotten injured anyway. He's still useful. I think worst case scenario is that he's healthy at the start of next season and he's where he is now.

Didn't even notice his age, whoops!