If the effort is too large then you might take years to get to the end - always trying to match the old product (which evolves) and eventually realising that yo

If the effort is too large then you might take years to get to the end - always trying to match the old product (which evolves) and eventually realising that your new architecture isn't perfect either. I think it can be extremely good to rewrite small things - you always know how to do it better after you've done it once.