Searing boeuf bourguignon
There's two things you really need to control, the moisture of the surface of the beef and the heat / fat content of the pan. 

Always pat beef down with a paper kitchen towel (or whatever else you use) prior to seasoning it and searing it. It will sear considerably faster if you do this, which results in you having less time per batch for the fonde to burn. 

The second thing you have to do is keep an eye on when your pan gets back up to temperature after you put your next batch in, and quite possibly lower the heat a bit (and even perhaps add a tiny bit more fat). 

But there's also the possibility that 3 large batches is just going to be quite difficult using one pan, so you could use two pans, or deglaze the pan after the second batch and save it (not ideal, but better than losing all that flavor).

I've never done more than two large pan fulls in a single go (I'd probably use a griddle that sits over 2 burners instead, if I had that much to sear).