Ok mate thanks for that.
It's just a mate of mine is trying to get me to resist riding hard in any way (i.e., not near, at or above lactate threshold - only well in the aerobic zone) for at least a month to build the endurance base.
He reckons even if you do your steady base miles at the weekend and then do, say, an intervals or hill sesh in the week, the latter will 'interfere' with the work of the former in developing the aerobic system.
By doing high-intensity work alongside aerobic work (he says) your speeds at and above lactate might improve but you will remain a less efficient rider aerobically. The idea being that what we all want to do is to maintain high speeds while still ticking over nicely at relatively low HRs.
Whereas I have always been of the opinion that you do your long base miles at the weekend and complement that with shorter periods of high intensity work in the week.
I do fear that I don't do enough long steady miles - because even at the weekend out with the club run, I'm working pretty hard to keep up with the fast group. Like, I'm puffing away and they're pretty serene.
It's just always seemed to me that if you can ride 3 hours at 18 mph, then why ride 3 hours at 15mph?