It's very approximate. You've Spain which has almost +3 hours of offset in the west of the country with the sun during DST, while you have countries like Japan which are in the negative territory (Tokyo).
Or, you have Spanish people who start their dinner at 10PM while Germans living in the same timezone are already sleeping at that time...
Or, you have Spanish people who start their dinner at 10PM while Germans living in the same timezone are already sleeping at that time...