...said management's historical inability to hold to their stated timelines.
Or maybe it's the case that the unknown is dictating timelines, in spite of their intention to stick to a schedule.
Seems to me that proving the ground is an ever-changing stop/start process of drilling/testing/assessing/
backtracking/evaluating/remodelling in order to firm up every target, piece by painstaking piece.
Such an approach would inevitably sabotage fixed timelines, rendering them guidelines at best.