Matt,
Any time you use an artificial lure or deterrent you need to do something to prevent the offending critter(s) from getting used to it.
My baby snakes are part of a rotating group of deterrents. Shiny metal, balloons with eyes, motion sensor lights, etc. all run the risk of loosing their effectiveness due to habituation.
Squirrels and some birds are very intelligent and just leaving these little snakes sitting on a branch for days will end in them loosing their effectiveness. But I don't do that. And because I don't they are very effective. I have not lost figs that were/are guarded by my methodology so far this year.
This does not mean I don't loose some figs - I do - but I loose the ones I don't covet, the ones I don't actively protect. I'm selfish with my favorites and a bit loose with some of the others. But so far my snakes have done an excellent job.
I've collected those blueberry containers and have them on hand should I need them, but so far so good.
thx
mgg