Standard Dynamics only allows users to create a Works Orders from an Opportunities or Case, but not a quote.
Quote Manager from CRM Dynamics has an addon that allows the user to create a standard Works Order from the quotation.
Why is this important?
The reality of the sales process is that, buyer will not sign a Contract or supply a Purchase Order unless they receive an official quotation.
Also, during the quoting process you may submit more than one quote and the quote might need one or more revisions before the seller and buyer finalise the agreement.
In terms of generating a Works order from a case, again, it would be the best practice to send the client a quotation and receive acknowledgment (signature or PO) before a works order is generated if the works will incur fees. So this should also involve a quotation.
Based on this premise, it makes no sense to create the works order from the Opportunity or Case if the resultant work involves an unplanned charge for the client, the quote is the best place to generate the Works order.