Oh! seems like this thread generated quite some interest.

Interesting to see I am right on the upper end of average given other's replies. I had read through the another cycling forum and was reading how their averages, at any age, were like 6-10 hours or something like that.
Not that I am competing to be up there with anyone else as I ride alone anyway! As per my OP it is due to feeling like there are different vistas just beyond the next brow I have yet to explore.
Four hours is a long while to go without food, if you stop to eat you might find you're more in the mood for going further.
The most I'd generally do without food was a couple of hours. In a three hour ride I'd stop to eat once, and anything more than that I'd stop for about ten minutes in every hour. As far as mileage goes, how many miles a day depends on how many days I'm keeping it up for.
I would say water is the more important and 4 is comfortable for me. I used to only go on 500ml but since got myself 2x 1200ml bottles and much better for it. 1200ml is probably ok for a 4 hourer out of summer I have found on the last few rides but the extra one is there for longer/hotter rides.
I can ride for about 30 miles or three hours, whichever comes first
Ah this is where I have little idea how far I am going, apart from a rough one, and will be interested to know once I get my odometer.
I like going out all day, but don't cycle for more than an hour to hour and a half in one stint. I need to give my bum a break, have a drink, something to eat and walk around a bit before going on. Something like 8 hours in all is quite doable.
Oh, indeed. For such a ride stops to take in sites would be a given for me. Also that is partly why I like paper maps. It is part of the experience to park up the bike and look at the sites by a farm gate while checking where I am. Imo, better than head down on a garmin or whatever they are called.
For me I would envision stop at 4 hours to eat and take in the surroundings and stop every now and then whenever I feel like it along the way for a quick drink or map check or whatever I feel like.
Also as to comfort stops, I am in my 40s but always been frequent in that department, up to 30 minutes at a time, which is usually more in the morning then settles down after that as the day goes on. Been told I should 'get it checked' which I have in the past but just one of those things they said if it doesn't bother you then just leave it, as any interventions would have more risks for something which is not causing apparent harm, which I have.
It has made me be reticent sometimes about doing activities with others as I know it would seem 'odd' though friends in the past I found get used to my constant stops after a bit. Maybe I should just ride with the old boys and we will all be hedge diving in unison!