I bet you think you have a good memory and maybe you do. You can remember what colour you used for that camo scheme last week or what kind of flock you used on that base last month. But what about in 3 months time or a year from now when you finally get around to adding a new unit to your army. I for one have struggled trying to match paints or basing materials on many occasions.
So now I don’t bother relying on my memory.
Just buy a cheap card index box and some cards and you can record all those detail you might just one day need again.
Mine has details of cloth colours from one off models, vehicle paint schemes, base materials and even suppliers for odd conversion bits. I just organise mine with index cards to help me locate the card I need in a hurry. In the years I’ve had mine it’s become an invaluable resource that I wouldn’t be without.