The way that I read A2.4:2007
‘6.2.7 Depth of Bevel Specified, Groove weld Size Not Specified. A welding symbol with a depth of bevel specified, and groove weld size not included and not specified elsewhere, may be used to specify a groove weld size not less than the depth of bevel.”
The word “may” make this spec. kind of ambiguous, which kind of validates Al’s response. Often in the factories that I work in, I find that there are usually additional notes on the print such as “all welds to X size”. Typically I find that after discussion with the print detailer that the Groove Weld symbol use on the skewed joint is an attempt to specify to fill the groove of the joint orientation to flush to achieve 3/8” weld throat.
Check out this interesting article.
http://www.weldinginnovation.com/pdfs/papers/design_file102.pdf