As JJ has already stated...the 'original' holes are more than adequate....
it is only thru a build up of grime n dust that the holes get blocked.
Extra holes are not a good idea. They'll block up with time just the same.
So a once a year (or every 2 year) poke with a small zip tie is really the
proper remedy/answer/cure. (zip ties are plastic, so they won't do any damage)