I believe the majority of fans (who buy such) would prefer everything at once.
With the number of fans who cry poor-mouth at every announcement, I doubt it.
All-at-once is not helpful to retailers either. No shop wants dusty stock clogging the shelves, or one series overpowering other titles. Packaging can get very dated very quickly. For a series on DVD/Blu-Ray, they want something new and vibrant each month
to promote on their "New Releases" shelves.
All-at-once releases would go on discount all-at-once, too, and then vanish from shelves all-at-once as other brand new releases demand shelf space.