More than on this drawing itself, I would advise against using the grid method, because it does not help you at all to understand what you are drawing, leading you to simply copy what you see. The drawing you posted is a good copy of the photo, certainly, but what have you understood about the way a hand is structured and positioned in space? Before you worry about accuracy of measurement, worry about gesture and construction, so that you can get more dynamic images, learn the structure of the hand and be able, if necessary, to exaggerate or vary the pose. The purpose of the grid is to allow you to reproduce as faithfully as possible or to enlarge an image that you intend to copy, I did this for years at school (I used it a lot in fresco), but it's not really useful for learning to draw, it's just a tool like a light table, a sheet of acetate or the dusting for a fresco can be. It's just a tool like a light table, a sheet of acetate or a dusting for a fresco. And relying on it too much doesn't really help you develop your ability to observe and process what you see. Sure, it allows you to make final images that appear satisfactory, but in your learning process it actually hinders you. It was used a lot before the new technologies because, for example, there was no alternative method, I don't know, to put a very small image on a larger surface, it is something that is useful to know but only worth using in certain cases (and today we have better and more precise alternatives).

This is an excellent study.

Nice approach. I like the way you showed structure and perspective to the hand especially the knuckles and fingers fat pads while avoiding symetry. However in my opinion you forgot that tedons on doso side of the palmar fat pads at the bottom of the fingers start right in the middle of the first metacarpals which should have been used to show tension from index finger. Also they can not allow the finger to split that much.

Please give me your advice. I take the photo of my hand and then use the grid system to measure the accurate shape. Critique is appreciated!