Yes, yes, yes, write every recipe down and date it!
I found a small tub of bits and pieces of soap, weird cuts and end cuts. I started using them up as hand soaps and one stood out. I really liked it and didn't remember the scent.
I went back and back in my notes and found the recipe and the soap just held enough scent for me to pin point it. I had in my notes that it was nothing remarkable, took a LONG time to trace and was squishy for a long time.
However, after many months it was rock hard and the lather was wonderful with a nice clean rinse (hubby wants NO oils left after rinsing). It was one of my first soaps and I didn't know that high olive oil recipes needed a longer cure. Live and learn... It's now a recipe I make for my husband to travel with...but I give it a 9 month cure!