I use the snake roll a lot with long bellied lines (XLT in particular).
When I`m on still water, I nearly always use the snake roll for change of direction (30-40 degrees), when practicing my spey casting.
I find it easier to execute than the double spey, (when being repetitive) although I tend to use the double more when fishing.
With a lot of line out, (or with sunk line) I find a double snake or a larger spiral to work well.
Luck, is when preparation meets opportunity.