PB or not PB...that is the question

I'm probably going to come across as a right ass here but fook it but want to point out a few things that might merit consideration

1) You are sick a lot
2) Your race performances are all over the place in consistency- one week you run close to PB, a week or two later, you are nearly two minutes slower
3)You have weak endurance
4)often your intervals are slower than your daily runs
5) Training is inconsistent in the bigger picture due to missed time
6) You get into peak shape and fall off a lot every year
7) You run fast all the time

Being honest, I think everyone of those are linked to the last one. I'm sorry for being so blunt as it hurts me to see you going through the same loop over and over again. I'm a firm believer in that if something isn't working, you change it. High intensity all the time like you are doing will lead to inevitable bouts of sickness as it pummels your immune system, it also hammers your central nervous system which basically controls everything in your body and when it gets tired, it shuts down shop and leads to it shutting down your muscles, punish it for long enough and it can take years to recover.

The ph of your blood is massively important in controlling your metabolism which is one of the most important mechanism in the human body and has a very small optimal range. When you train like you do every day with that burning lactate accumlating, it starts to mess with the acidity of your blood. Lactate produces a wate product called hydrogen ions and pH stands for potential of hydrogen so the more you run at paces that cause that lactate burn, the lower your blood ph falls until it's well outside optimal which will cause chronic fatigue, much higher potential for viruses and bacteria to flourish and breaking down of muscle and bone density(it makes you weak). Think what happens if you were to feed a plant acid, it starts to break down, your blood is what feeds your muscles and organs.

For a 10k run, the aerobic contribution is almost 90%. This means that endurance is more important than speedwork and that should be reflected in training, aerobic(around marathon pace and slower) training should be the main focus of most of your week, aerobic fitness also the effect of lower blood ph as if your body can use more oxygen, it becomes more efficient at everything from fighting illness to how calm you feel to how fast you can run 10k to running better speedwork as your body can clear lactate faster.

I know you have time constraints but slowing down 30 seconds per k on a 10k run is only 5 minutes more of running but I personally guarantee it will completely alter everyone of those points I mentioned above in a postive way by an order of 100 times magnitude. You are currently hammering your body and it doesn't like it at all which ijs why it's giving you all those signs. Doing so will not be a loss of quality from your training but it will be getting it back in balance and it will pay you back tenfold for it, slow miles are not junk miles, Eliud Kipchoge runs 80% of his mileage at marathon pace or slower and even he is an extreme example compared to what mere mortals should be doing.

Even look at your clubmates to see what they are doing. MC is running 4 min pace or slower most days and he's a sub-70 half guy. NOR is running anywhere between 3:40 and 5 minute pace with the majority slower than 4:30 and he ran 15:40 a cople of weeks back. NS is running between 3:20 and 4:20 pace with most over 3:50 pace and he ran 51 for 10 miles. SD runs 4 min pace most days and look what he done over the winter. It's not giving up quality, it's gaining endurance. I honestly think if applied this to training, you would run much faster than your current PB's by a long way and you would 100 times more consistent. Just my 2c.