By writing well communicated information, with proper context, you save multitudes of time in the long run.
If you don't do this, you're forced into re-explaining context repeatedly. The time spent doing this adds up, and is not only your time but the time of every other person you talk to. Extrapolated across different meetings with various amounts of people, you're consuming a lot of time for something that can be explained once, and explained asynchronously.
Communciation is always multiplicative, so get ahead of the curve and write early. This also applies to when asking for help - give the required information and context that doesn't require everyone that views your message/email/etc to do the legwork individually.