@DopeyBadger Okay! I normally slow down for my longer runs if I’m struggling but thought I needed to push through it for the speed days- otherwise they wouldn’t actually be speed days. I’m not sure how much of that feeling like I’m gonna puke i should be willing to suck it up and tolerate.
So the way it'll work best is to use the T+D chart first. So easy days, long run days, tempo days, speed days, essentially every day. You look at the scheduled pace, and then the pace from the T+D chart and it gives you a general idea where you should be. Then during the actual training, you use that pace, and the knowledge of what other days "felt" like to decide on today's correct pace. So sometimes it might be slower than the T+D adjusted pace. And almost on all occasions, I don't want you to go faster than the T+D adjusted pace even if it feels alight. Commonly this happens with easy days, where people take the easy days a touch harder because they can. So something like, I have to adjust hard days because they're hard, but I don't have to adjust easy days because they're easy. Commonly that makes the easy days harder than intended.
So with that out of the way. Once you know to look for an adjusted pace regardless of the type, and an effort based on previous experience, then you see what the first split is. The goal is to remain consistent across the whole workout. Avoid the fade. And at the end, if you felt like you could have done "one more", then you did it right. Speed workouts can be slower than the originally scheduled pace and still do exactly what it was intended. In fact, running a speed workout in a T+D of 150 at the original pace goal is way more likely to cause the run not to be what was intended in the first place.
When I was running mid-summer in peak training, my faster workouts were 20-40 seconds per mile slower than originally scheduled. But my effort was spot on, my HR as a secondary measure was spot on, I had consistent splits, and felt like I could have done one more. And as the summer progressed I was getting faster and stronger.
So are you completing the workout with all splits being consistent and feeling like you could have done one more? If so, then you're probably doing fine.