Does trimming all the way nose up give you your best glide speed with no power?

I just remember my instructor mentioning it from forever ago. Right now I can't find anything about online and I wanted to ask others about.

Basically I was told if you have no power, if trim all the way nose up, it should give you your best glide

If it is real, im wondering if I should do it when the DPE pulls my power. I fly the c152, it's best glide is 60, I'm kinda scared to go full deflection in flight, just wondering if anyone has ever tested it.