Love Liman has a short article on this site pertaining to Japanese Woodblock Prints ( Article ), and in it he/she(?sorry?) states that:

"As a measurement of the necessary skill for carving, it can be mentioned that an apprenticeship of about ten years was required before a carver was considered to have mastered the craft."

I'm posting this thread to see if Love Liman them-self, or any other viewer for that matter, can tell me where they obtained this information? I tried all the reference links at the bottom of the article, but none of them seem to go into this kind of detail.
I've been trying for some time to research the training and lifestyle of the ukiyo-e block-carvers themselves (as opposed to the "artists") during the Edo period, but have only met repeated roadblocks, so whatever source this information came from could prove to be invaluable.
Thanks for your time all!