Is stratification necessary?

I purchased the cutest little kit for growing carnivorous plants from seeds today. The directions say to straifi the seeds in the refrigerator for 8 weeks. Later in the instructions it say seeds should sprout in 3 to 6 weeks if you don't stratfi. Which is best? The kit contains seeds for Dionaea muscipula, Darlingtoni calfiomica, Sarracenia flava, Sarracenia minor, Sarracenia rubra, Sarracenia purpurea, Sarracenia alata, Drosera intermedia, Drosera filiformis and Drosera rotundifolia. Any suggestions?

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