Depending on your seniority it would be advisable to bid all 52 weeks as choices, but I think it's bad advice to try to get all of your available vacation weeks awarded in the primary cycle, unless you want just one or two blocks. By definition with how the primary cycle works, you would only be able to get at most two vacation blocks this way. Or inadvertently one if the two blocks are adjacent. For someone trying to spread vacation throughout the year more you would need to get vacation awarded in more than one bidding cycle. Sure, the good weeks will be gone after the primary cycle, maybe even during the primary cycle if you're junior, but you can still work to spread the weeks out in different months for QOL purposes.