I thought this was an interesting article, in which Bay once again confesses to not following scripts when he gets visual inspirations while on the sets... mentioning that Speilberg even tried to tell him to stick to the script, but stubbornly rejected the request, claiming that even if 80% is screwed up by improvising the script during filming, at least there is 20% that is "gold".

(yeah, that's a good performance requirement there... aim for a good 20% of "gold" instead of, you know, 100%)