Long ago I started my city when there was nothing.
I did poor job, but I mapped streets in parts of the city I lived until then.
One or two years ago people fixed my mistakes and mapped the rest of the city. I consider it huge success, so just start and others will come and add more details.
It was great feeling, calming and fun. And addicting.
Haven’t done anything recent since all locations I am familiar with are now mapped to great details.