Although I can be a bit more flexible in my schedule I can see this is an issue for several people on my friendslist. Having the locations locked on the same dates and the dates corresponding with certain times outside the game means people that play at the same times will only ever experience one, maybe two different skeleton ships. I think it's nice that Rare added the dated commendations to make sure people will be playing each week of the event, however you need to defeat each skeleton crew each week. This will be impossible for those that can only play at a certain time.
Just one other things that I see in the replies/topics of some around this subject:
This isn't about wanting Rare to cater to specific needs, It's about asking Rare to respect the time people spend on their game without forcing them to play at set times. People that only play in the evening could spend maybe 5 hours a day, so 35 hours a week and still never be able to see one of the skeleton ship battles.
The solution to this issue seems quite simple:
Rotate the dates of when the ships spawn every actual day and everyone that plays at the same times will go to fight at a different location.