I did RL and evals at Amazon for a bit on Nova Forge (laid off in July! :D). I would have to push several thousand lines of code a day in new evaluations that our applied scientists requested since new ones are always being made along with having to create custom ones for whatever new model they were working on. Also, in RL, adding new environments for the agents to actually complete activates was also a shit ton of lines of code. So if I had to guess, just adding new stuff around model training and testing alone accounts for a ton of these changes.