When people say same day they are usually talking about a couriered application. If they say 20-40 days, they would not have used a courier (from the accounts of people on the forum here over the last 2 years, I haven't heard of any courier-sent applications take longer than 5 days maximum - most seem to have been approved within 48 hours).
As I understand it, usual wait times (with no delays) are:
24-48 hours with courier,
1 to 3 weeks without courier.
If the consulates are busy you might be looking at:
3-5 days with a courier,
maybe 3-5 weeks without a courier.
ETA: I'm using estimated times based on straight-forward applications.