Depends entirely on what you're cutting. The blade will last quite awhile with regular sign vinyl or heat press vinyl. Getting into specialty materials may ruin it very quickly. Chromed vinyl, glitter vinyl, any kind of metallic. The absolute worst is reflective sign vinyl. It is created with glass beads, so you're basically ramming your blade through a bed of glass that's been glued together (glass cutting boards will kill your kitchen knives!).
If you bought a scrapbooking cutter or use a regular cutter to cut out paper and cardstock, this will create heavy wear on the blade too.