I weigh 171 pounds now. I will exercise before it gets too hot outside, maybe anywhere from two to four miles doing my run intervals.
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My concern is IMO heart rate definitely needs to be considered. Fitness level is important too. Of course both can loosely correlate. This would also handle that case where you are tired but still pushing yourself to go further. This is where calories burned per mile increases. The question in my case is how much of a difference will this make?

According to your references, I would be burning 110 calories per mile, which on the surface sounds “reasonable”. Keep in mind a person of your fitness level will be noticeably less as I have seen by how you adjust calories down very significantly. Perhaps the calorie estimates you have been getting would still be high for you even not considering your fitness level? So if this 110 is valid, I think it would be reasonable to assume that in my case I am burning more calories per mile.

On average, how much have you had to adjust those calorie estimates down for yourself? I have seen you halve them. There are times you take what appears to be significant exercise and not log them at all. This still worked for you, but you were trying to lose weight at the time. You are now using 50 calories per mile for walking. Your calculations based on that calorie calculator in that article results in over 90 calories per mile burned while walking. I do not think your excellent fitness level can explain all of this difference. Using you as an example, just allowing for differences in fitness level, I still could be burning much less than 100 calories per mile.