"YOU"...Sounds kind of accusatory!
Here is my experience. Round balls rarely get me the kinds of blood trails I get with black powder conicals or paper patched bullets, and especially compared to modern centerfire. Smaller round balls get less blood than a .54 round ball, which also doesn't leave a real big trail in my experience. Where I hunt in the deciduous mountain forests of the east, a light blood trail without snow is very difficult to follow. Took me years of hunting with a .45 Pedersoli to figure out I needed to follow up on every shot, that just because the deer ran away with its tail up did not mean it was not hit. And that just because I did not find blood or hair where the deer was standing did not mean I had not hit it and that it was not lying dead 100 yards away. So following up on each shot and walking in the direction of the deer's run is something I now do every time I shoot at a deer with a muzzleloader. It should be a rule of thumb for all muzzleloading hunters, though everyone learns at their own pace. Interestingly, the flintlock or percussion British Sporting Rifle of the 1790s to the 1860s was typically 20 gauge (.62 caliber), 14 gauge, 16 gauge, or 12 gauge (.72 caliber), and that was just for hunting red stag, fallow deer, and roe deer. Similar to the German jaeger rifles, that started at .54 caliber and quickly arrived at .72 caliber round ball. Seems that the European hunters desired to anchor their quarry and not have much time spent on a blood trail. While I have hunted with a .54 flintlock since 2013, I am hoping to have a .62 caliber flintlock in my hands before December this year. It will be based on the British Sporting Rifle design, and yeah, I was even thinking of going to .66 caliber.
And to be fair to muzzleloaders, I have experienced very recently "updated" modern bullet designs out of modern centerfire rifles that left very little blood trail, with me pacing back and forth on the mountain trying to find a deer that is already stone cold dead 75 yards away, such is their ability to mushroom up inside the deer. That also is a disadvantage, and I prefer a pass-through with blood leaking out of both sides.