My son did an experiment last year on egg viability and time. It was fairly successful, although I wish we had used spitzies eggs instead of orps ones. (My spitzies always have 100% fertility while orps are more....finicky) However, I think he set 5 at 1 day. 5 at 3 day, 5 at 1 week, 5 at 2 week, and 5 at 3 week. 1 day, 3 day, 1 week all had development and two week had 3 I think. My 3 week eggs had two develop, but one quit. I cannot remember if the other quit or hatched. So the day 10 rule does seem best and viability does seem to drop after a week to 10 days. I believe Faradays DS is doing a similar experiment this year for his 4h project.
I set 24 spitz eggs for the Easter hatchalong. My 5 girls are laying everyday, so it was fairly easy for me to collect enough under the 1 week boundary. Yesterday was day 14 and all except 1 are doing well. The one looks like it quit at around day 10-11 and possibly deformed. It was from a pullet egg. I tried to set eggs from my older girls, but still had 2 or 3 pullet eggs in there.
Hope this helps.
I set 24 spitz eggs for the Easter hatchalong. My 5 girls are laying everyday, so it was fairly easy for me to collect enough under the 1 week boundary. Yesterday was day 14 and all except 1 are doing well. The one looks like it quit at around day 10-11 and possibly deformed. It was from a pullet egg. I tried to set eggs from my older girls, but still had 2 or 3 pullet eggs in there.
Hope this helps.