The fully loaded cost of a senior engineer is already well past 400k. +5k a month is not that much if it helps them be XX% more productive. Personally at a different big tech I'm in the mid 4 digits AI spend per month and it helps me a lot, basically all coding has been trivialized and I work on an extremely large codebase. I'm spending more time on things closer to direct value generation like data analysis and experiment tweaking rather than spending time moving a variable across 10 layers of abstraction and making sure code compiles.