This is a sure way to fool oneself, especially if they already have a thickness number in mind.
I object to this wild comment.
I am sure you have never handled Por. India Cor˘a or Ceres keytype issues. Anyone serious about these stamps will know how important is paper thickness to differentiate array of differenet papers (sometimes thicknesses differ in same type of paper) and there is specialist literatures on the paper thickness of Por. Colonies Cor˘a/Ceres stamps including ═ndia.
It is absolutely OK (nothing foolish about it) if one has a number (recorded range) in mind when measuring paper thickness of postage stamps. What matters is the mastering the use of micrometer (SAFE 9680 Digital Micrometer I mentioned, specifically prepared for stamps but outrightly rejected by the OP) which requires some practice.
There is a children's comedy classic literature in Bangla language (my mother tongue) titled "Heshoram Hushiyarer Diary" by Sukumar Ray (1887-1923) where a character named Chandrakhai, the nephew of the protagonist Professor Heshoram during his expedition to an unidentified location near Bandikush Mountain (fictional place based on Hindukush), measured the height of a hill by trigonometrical survey calculation at "42000 feet".
Realizing that world's highest mountain Mt. Everest is only 29000 feet, after several recalculations yielding different results every time, the height was finally calculated at only 2700 feet.
So, a "range" guide is always helpful.