The most amount of push while swimming in breaststroke is the one you get on finishing one loop cleanly by connecting your legs. Leave it half and go for another stroke, thinking the hands or the kick of the legs are more important and you squander the benefit generated by the least amount of effort that comes from completing a loop cleanly.
The last push that allows you to cross the finish line, be it in a sprint or a project will be the one that you will benefit most from. 100m at the end of a sprint are more important than the 700 that preceded them in terms of the returns they give you. Not just material gains but immense learning and self-confidence and the potential to build on top of something that has already been achieved are the treasures of finishing. It is really an all or nothing gig most of the times.