No faster, too consistent?

I've been running a loop around Dore for 3 weeks now. I had hoped that I'd be getting a little faster by now but oddly my fastest time was my second try on the circuit.

On the first time the ground was icy so that would never be quick. So what's going on? Inclusion of this loop has involved an increase in distance and time during the week, so I am training harder and doing more, so recovery becomes more of an issue. As a component of this, I'm also swimming to improve fitness but not wear my joints too much. Best part of 40 years ago I was probably a good swimmer, but since then my skill has steadily diminished. Now I find swimming hard work, especially linking strokes to breathing so I don't build up too much of an oxygen debt. I'm getting some guidance on technique but that merely serves to require me to keep going!

Metronome by Vera Kratochvil

Also my speed seems pretty consistent, I do slow down uphill, but on inclines and level, at 0km and 15km I'm going at very much the same pace. I think it is now possibly too constant  and has been reinforced by repeated runs of similar length, around 10km to 18km, rarely much less, nor much more. Too much routine. Lots of training plans that I've seen include variety and require changes of pace to help break such barriers. The problem now is that I'm in a comfort zone.

On the bright side though, I have added time and distance without much of a problem and that is a key outcome. My long term goal is distance, and not speed, after all.