Scott, for me the best strategy is to identify my goal for each set I am starting to build. The 72 set is my favorite set from the 70s and the first "challenging" set I ever completed. In the early 2000's my goal was to complete this set in the raw fashion. However, I ended up with a few of the stars graded as they were the best option(I did not free them as Al does). A few years after completing the mainly raw set, because of the graded stars I had, I decided on a new goal to finish the set in the graded format. It took me a few years to complete the set in the graded format and I enjoyed every minute of the challenge of building this set in that manner.
http://www.psacard.com/PSASETREGISTR...et.aspx?s=3092
For me establishing a goal as to how I wanted to finish the set was just as important as finishing the set. There is no wrong or right goal....just whatever you feel is right.
In the case of the 72 set, NM raw commons are fairly common/relatively easily found and can be had for 10-20% of the cost of a graded common. Your question would be is it worth spending 5 to 10x more per common in the graded format, or collecting the same quality of card raw (untombed)?
If I had it to do all over again, I would have stuck with my original goal of building the set raw and settling for a few of the key cards/stars graded.