If you can't remember what's in the package you didn't really need it

So many times people tell me "If you can't remember what's in the package you didn't really need it".

I just received a package. Could not remember what it was. I tried really hard to remember before opening it and I could not think what it was.

Going by that general rule of if I can't remember what it is, I didn't really need it right?

Just opened it, it's a bath mat. My last bath mat got completely destroyed and I had to throw it in the bin on Wednesday. Now I remember that every time I took a shower or washed my face at the sink since then I had remembered that I really needed a bath mat!

I think most people could agree that as I didn't have a bath mat anymore, I do really need this new one.

So, I think it's because I have ADHD that I can't go by the if you can't remember what it is rule... What do you think? And are there any better rules for us adhders to follow to know if we really need something?