There was a project that I was on that we should have spent more time in the research phase. We were culturing cells for this project and there was one very old article that we found a few weeks after the project had finished that mentioned that we should try to culture the cells in spinner flasks and that would increase the growth rate of the cells because they were in suspension and not attached. Once we ran this test it was clear that this was a better route to take and we updated everything after the fact which cost us some more money but saved overall in the end.