I've started using Jack Daniels' training plan for 1500m to 2 Miles for about 50 to 60 km a week. That's my first time using his programs. For phase I building the aerobic base, I had no problem accumulating easy mileage and doing some strides. I'm not using Daniels' E pace for my easy runs, but rather going by feel and using a heart rate monitor to make sure I don't go over zone 2 (although I'm probably in zone 1 half of the time), and usually my average pace is just slightly slower than the slowest pace Daniels' considers E pace for me, but that's also because I don't do my easy runs on the track or on a flat route, but rather anywhere in the roads of my city which has lots of ups and downs and I also usually don't take any caffeine before easy runs. Moreover, Daniels himself says that you want your easy runs to be as easy as possible as long as you don't run with bad mechanics, so I'm not too worried if my E pace is slightly slower than his suggestion.
But my problem started a few weeks ago, when I started phase II of the program, where R pace workouts are introduced. As I understand it, R pace should be about your Mile race pace, so although it is a pretty fast and hard pace, it's not a sprint or max effort. Nevertheless it feels to me like this pace is usually too hard for me. In a few of the reps workouts, when I felt particularly good I managed keep this pace for all of the reps and the effort felt right - hard but not maximal, but in most of the workouts this pace felt just too hard, like there's no way I could run a mile in this pace on that given day, and I don't want to make this workout an all out effort, because I know it shouldn't be that hard. My paces are calculated based on a 3,000m race I ran approximately 3 to 4 months ago, so I know that this data is not the most recent and accurate, and I do plan a time trial in the end of phase II, but overall, I think this race is a good data, because I feel like I'm now in just a slightly better fitness than shortly before this race (although that's just a feeling). I think that the problem is that I had nearly perfect conditions for this race, which are very hard for me to replicate in my workouts: perfect temperature (in my workouts the temperature is usually slightly warmer than ideal), I was tapered and very well rested, I had a ton of caffeine (in my R workouts, I take a bit less caffeine), I was slightly lighter than usual mainly because the race was early on the morning so I had a mostly empty stomach (I do my workouts in the afternoon / evening after I already ate breakfast and lunch although I try to make the meals smaller on these days). So, although I definitely think I could race a mile in this pace under good racing conditions with a good taper (in fact the last km of my 3,000m a few months ago, was in about this pace), I think it's too hard for me for normal training usually.
Is it normal to have a substantial performance difference between racing and training? And how could I know what's the right effort for me to go on reps? Is there some heart rate range that I should be in, or some cues for how hard this effort should feel? Do you have any other suggestions how to deal with this issue?