The electronic sign at the metro station tell you that your metro will be there in just one minute. And you are probably wondering if it still makes sense to run for it. Well even if one minute sounds quite tight, you might have quite a good chance.
The reason is that the electronic signs at the entrance of Helsinki's metro stations don't show the same time as the ones downstairs. They still calculate in the time you need to get down the escalators. So don't hurry next time it looks as if you won't make it. If the metro is still announced at the entrance of the station you have a pretty good chance of still catching it.