I invested some time and effort researching EK's policies re awards and upgrades and I would appreciate confirmation that what I have understood is correct, and (even more valuable) a correction of what I got wrong.

Here is what I understand:

1. EK uses booking class O to designate Business Flex+ (aka "classic") award tickets. They use booking class D to designate Business Saver award tickets AND also for Y cash tickets upgraded upgrades to J. Confusingly, O can also be for a Business Saver ticket paid for in cash.

2. Upgrades of cash tickets in Y to J come from the same "bucket" as Business Saver Awards. This means that the surest way of searching for upgrade availability is to search for awards: if they show Business Saver awards available, you can get an upgrade using miles.

3. Naturally, Business Flex+ awards are noticeably more expensive than Business Saver awards / upgrades. Consequently, if both are available, it is a more economically efficient usage of miles to get a Business Saver award or purchase a ticket for cash in Y and use miles to upgrade to J, rather than seek a "classic" award ticket.

4. Since the upgrade costs the same number of miles as a full Business Saver award, presumably it is always more economically efficient (in total usage of miles plus cash) to go for the award rather than the upgrade.

5. The logical conclusion therefore is that it makes no sense economically to seek an upgrade; a Business Saver award is always better.

6. There is a far better chance of finding availability in O class than in D class. Seeking a Business Saver award is EK's equivalent to searching for the proverbial needle, almost. The majority of the usage of miles on EK is for the "classic" or "full fare" awards.

7. This analysis applies to when planning ahead and searching for and purchasing tickets in advance.

Is my above understanding and analysis correct?

What is not clear to me is:

1. When does EK make D class seats available? Is it 11 months before? 5 months? 3 months? Or they do it in batches?

2. The cash paid in addition to the miles when issuing an Award ticket: is it the taxes and government charges or is it "padded" with other fees and charges?

3. When offered an upgrade on the spot upon check in or when boarding: is the number of miles deducted equivalent to the Saver Award? The Flex+ Award? different.

Apologies if this topic had been addressed before and I look forward to learning from the experts.