My times do not count stops, I suspect your were, I never advise on averages including stops as how often and how long to stop is a very individual thing as covered by others in this thread.
I work on an average of 15 minutes stopped for every hour riding and allow an extra 30-45 minutes for the lunch stop, making my preferred ride times between 5 and 6 hours (7-8 hours total) this gives a relaxing day / time to deal with unexpected delays / time to stop if we come across something interesting. This seems to work out very accurate FOR ME, as stated by JohnnyBoxer, it takes years to hone this.
My speeds are based on 10 years European touring and from of Sat-Nav data, I always log the miles and averages for each day, as Wapping states people travel at very different paces, but I have ridden solo / two up / on "Lads" trips / With the Mrs on her bike / in groups of varying abilities and found the speeds do not vary much from the centre line of those averages.
The sa-nav tip is great, I also use this, you can see the estimated arrival and know how much planned stoppage you have (like lunch) to add on to give a rough ETA, if this slips back too much you need to speed up / stop less, if it is getting shorter you can have that extra cuppa, or often I find if the weather is great and I am having a good day I might not care about getting there an hour later - but only because I avoid planning a 12 hour ride in the 1st place.