For you and others curious on the past POT runDisney system. Can't say definitively they will continue to use the same system.
POT (Proof of Time) Race Equivalency Cutoff Confirmed Times
View attachment 663828
An example on how to use the above:
A runner has a
1:58:00 HM time that is POT submittable.
-If they run the HM as a solo event and submit the 1:58 HM time, then they will be assigned s1. That is because the HM time is less than 2 hours. See bottom table.
-If they run the M as a solo event and submit the 1:58 HM time, then they will be assigned s3 for the M. That is because the HM time is between 1:53:46-2:07:48 which is the estimated bucket for s3.
-If they run Dopey and submit the 1:58 HM time, then they will be assigned s3 for the HM and M. That is because the HM time is between 1:53:46-2:07:48 which is the estimated bucket for s3.
In some years, the 1:58 HM POT would mean a s3 for the 5k/10k (despite having 5k/10k estimated paces at registration), and in other years they've assigned you based on the 5k/10k estimated pace submission at registration (editable up to the POT deadline).
So if you're running either the M/Goofy/Dopey, then you look at the top table. If you're running the HM as a solo event (or a HM Challenge weekend that doesn't include a M), then you look at the bottom table.
McMillan uses T2=T1 X (D2/D1)^1.07 for both the conversion of HM to M and for 10k to HM. So using the above table I've generated you can see there are advantages to submitting certain POT distances depending on the race you're doing.
-If you're doing the M/Goofy/Dopey, then it's most advantageous to submit a 10 miler. That's because the POT calculator they use for M/Goofy/Dopey treats all distances equally at a roughly 1.079 Riegel value. Since they're all equal in conversion, an individual runner is most likely to achieve the 10 miler time threshold before they can meet either the HM or M threshold. For an example above, it's more likely a runner can do a 1:35 10 miler than a 2:07 HM or 4:30 M.
-If you're doing the HM solo event (or a HM as part of a non-M challenge such as Fairy Tale), then it's more advantageous to aim for a 10 miler or M. The 10k appears to be receiving a conversion of 1.055 (pretty standard value). But the 10 miler and M oddly appear to be much lower at 1.015 and 1.124. So in my opinion you're more likely to hit the 10 mile or M time, than your are the 10k or HM time. For an example above, I think it's easier to hit a 1:42 10 miler or 4:54 M, then it is to hit a 2:15 HM or 1:01 10k.
Edit to Add - If you're ever curious about the POT cutoffs, reach out to runDisney. They will tell you where you fall using their calculator. They will not share the calculation. But an accumulation of data has allowed me to come up with a reasonable estimate.