The hosel depth of my Srixon 765 irons are the same. I know the correct shaft length for installation into my pitching wedge. Can I assume that by increasing each respective shaft (9 through 5 iron) by 1/2 inch I’ll achieve the correct finished club length for each of the remaining five clubs?

Answered question

It really depends on the shaft. If you are installing new shafts, you need to follow the trim code which will determine how much of the tip is trimmed, taper tip shafts generally aren’t tip trimmed. After that is determined and the shafts are tip trimmed (if necessary), you then trim the butt to length.
Most hosel depths are close to being the same. I generally dry-fit, measure length, mark and then cut.

I think that is what you’re asking