i usually get back about 30% total weight once dried, sometimes less but honestly just a guesstimation. Usually i will take a nice size nugget and weigh it right away and then check that same nug 5 days later. Never actually weighed the whole harvest wet (why would you?)
Just in answer to your question, why weight it when wet?
Wet weight can be use to estimate the final moisture content of the harvest. E.g., harvest wet weight was 100g, You normally lose around 75% of moisture/gases during drying, so you get 25grams dried. Now if you weight the wet harvest ever few days you could then say that when it gets to about 25g i can then jar it for curing. Or if you wanted to cure you buds with say 45% moisture content ( i saw this figure on another website,i wouldnt personally,sorry ranting now,) you simple jar it at 45g.
So there can be a use for it. We actually use this technique in grain harvesting/storage. Basically you take the M.C of the fresh grain harvest,(you actually do it before you combine it too), then dry it for however long(depends on drying method) and then measure M.C to see how much has dried, and you can dry it again or its ready for storage or sale etc.
(Edit. I guess you could do that with the single bud too but one bud may of dried more than other etc..)
take it easy.