Incidentally, one of the claims made by Julius Kirchoff for the "Franklin System of Steam Distribution" was that the exhaust cams of rotary-cam valve gear could be cut differently from the inlet cams, allowing longer release for lower compression while retaining quicker admission opening and prompt early cutoff. I believe that is also a feature of the evolved British Caprotti system (and may be something further addressable with the steam supply used to keep the exhaust valves seated).

See also the various kinds of compression relief used for drifting, ranging from Nicolai/Trofimov moving heads to the Prime system on the Reading T1s and the Wagner valves on some large ATSF classes.