I've had 5 recent bow kills where the shaft was snapped off as the off-side shoulder came back as the arrow was "passing through", snapping off the broad head and leaving the shaft sticking in the deer.
2 blade or WWoodies, I had dismal blood trails when the shaft plugged the hole.
Speaking to Ed Ashby on the topic, he pointed out some "sharp" heads are indeed, sharp going in but not so much so going out.
Now I sharpen with a 25* bevel instead of a 20* and with diligence (and KME equip) I get much, much sharper 2 blades.
On that note, I've read and heard all the "scary sharp" for 3 blade, but some I've seen weren't...and those that might be, I know I can't do it myself...so I go for blades that I can get super sharp,---that is a durable edge 2 blade.
Doesn't stop the issue where instant reaction on the off-side leg snaps the shaft and it remains inside the deer, plugging the hole... but I've had most deer die within 60 yards and either saw or heard them fall.
As Rc noted, pass throughs, where it didn't get snapped off...deer just mozied off and dropped over or jumped a few jumps and keeled over.
I think blood trails are related to fat layers too. Several years in a row, deer had so much fat on them, the low pass through hole was clogged with fat when retrieved.
Indeed...many variables. I'd say "shoot what YOU can get sharpest!"