Reasons for keeping a garden guide

You know those little plastic plant name tags that you find in the plants? I keep them. Last fall I purchased more than a dozen perenniels, and I dutifully kept the tags, but forgot to log in where I planted things like japanese anenemones and dwarf indigo. I have the tags but I can't remember where I planted the plants! Very frustrating. So, I'm making a mental note to use my garden journal with specific details for where I've planted. Those little plantic tags are there for a reason.