I would have thought that the various coders who have re-worked MMs 6-8 would have corrected this, but I guess they overlooked it.I didn't find a reference to this bug on these pages, but I think I might have copies of our earlier Taverns somewhere. If I can find them I'll search for a mention and post my findings here.
A 12-hour duration is what you'd expect with a skill level of 43.
Duration = 1hr + (.25 hr * # skill points) = (1 + 10.75) hours = 12 hours with rounding.
At level 43+21=64 you'd expect 1+(64/4)=17 hours, but the coding is completely ignoring the 16 hours from the skill points. I don't imagine that we can fix that, but I wonder what the maximum skill level is that the coding will recognize. Perhaps that info is in an old post.