Sorry, I expressed that completely wrong: it DID include the 17 minutes (for a total of 82 minutes)...

But to your main point:
I am finding that an average is not a very good measure of anything related to thresholds -- especially as it relates to bike riding. That is, 20 minutes at 160bpm and 20 minutes at 90bpm average out to 125 -- which tells you almost NOTHING about capacity.... (And with the long, roliing hills I ride on, that is a pretty common scenario)

But, to your point: I can hold a heart rate of 128-130 (or higher on a good day) for 20 or 30 minutes. Which, while not a formal test, I think says something about my overall capacity and my LT.

BUT, I am not sure I agree that LT values can be compared directly to VAT values. They are measuring different things: LT is measuring the amount of lactic acid in the blood. Which, by the way, indicates nothing in and of itself -- but it is an indicator of acidosis which DOES trigger physiologic responses. Meanwhile VAT can be measured in different ways, but it basically indicates a change in breaths per minute as well as a change in the relationship between CO2 and O2 in those breaths. CO2 is produced from both aerobic as well as anaerobic metabolism.

So, while VAT and LT both are trying to estimate aerobic capacity and sustainable power, I am not so sure that their individual numbers or percentages need to correlate. And, in addition, even the unit of measure changes the perentage: For example:

Measured in ml/kg/min my VAT is 50% of my VO2max using the same unit of measure (18.9 vs 38.1).
BUT
Measured in beats-per-minute my VAT is 83% (114 vs 138).

Since the LT is measured almost exclusively based on heart rate and it is measuring blood chemistry instead of ventilation parameters, it is hard to compare numbers.