By making the comparison I wasn't meaning to insinuate that you were doing too much, rather I just thought it was an interesting comparison. I don't have a very clear idea what other people do when training for a 50 or a 100, but I guess it's just about finding a personal balance between running as much as possible and limiting risk of injury. I have heard that some people prefer a single long run on the weekend but I found the split runs worked for me.
My biggest weeks in my hundred mile plan looked pretty similar to yours:
Monday: 10km (~6miles)
Tuesday: Intervals (~4miles)
Wednesday: 21km (~13miles)
Friday: 10km (~6miles)
Sat/Sun: ~50miles split over the weekend (e.g. 30/20, 25/25 etc.)*
That adds up to 79 miles and I don't think I could have run much more than that. I can't remember the details but I think the whole schedule was c.30 weeks and I tried it twice, although I was more relaxed about completing the full mileage the second time around - ironically I dnf'd on the first attempt and then finished the second attempt when I had been more relaxed about the training.
If you can complete that training then I'm pretty sure it'll stand you in good stead for your 50, but I wouldn't be too stressed about completing everything. There will be plenty of people on the start line who have done less than you, and if I get into the SDW50 then I'll be one of them :-).
*One thing to note is that my Sunday long runs often took far longer than expected. My running speed was ok, but once you factor in stopping for gates, navigation, hills etc on top of the fatigue from your existing training load... I think 30miles usually took more like 6hrs.