Sometimes its very easy to go a bit too hard on the easy sessions without realising if you have no numbers, and then you wonder why you can't hit the numbers on the hard sessions.
Sure is easy to overcook it, unless you're knackered.
We seem a lot more savvy about training than when I was a young lad racing on the local velodrome in the late 1980s. I was bought up the old school way for club 10s, that you just went as hard as you can. It worked well enough on the velodrome when races for a juvenile were never more than a mile and there were a few tactics going on to save yourself for the sprint finish. But for club 10s, I think that I started off too hard. The coach at the velodrome never talked about HR or effort, except that you just rode as hard as you could.
Track racing did get my speed up a bit, but never made much difference to my 10 mile times.
Going back to a few club 10s a few years ago with the same mentality and not using a HRM, I'm sure that I went straight into 95% MHR + for the first half a mile (I remember doing 25mph uphill from the start and not going any faster when it go flat, but being out of breath) then tried to recover, then going back up to 95% and so on. I did wonder why the fast lads didn't seem out of breath while I was gasping but put that down to not being used to short events.
Pacing myself never really occured to me for a 10.
Suppose I ought to try a club 10 this year with my HRM. I doubt I'd be much slower than a few years ago, unless I ride it backwards!