Agreed!
What you may have to learn with a bead sight is your hold on your target. Your point of aim (POA) may be on the bull, but your point of impact (POI) may be a few inches somewhere else. So you adjust where you hold your bead, your POA, and (assuming as MikeD said, youre consistent with how you hold the gun and aquire your sight picture), youll begin seein results in the way of shots on target, your POI will be where it needs to be.
Example;
My 590A1 groups (my POI) low recoil slugs about 3" low and 2" left of my POA. Si I adjust for 50 yards by holding my POA 3" high and 2" right of the intended target and then see POI withina 4 to 6" group centered around the bull. With a sight, you can adjust that to the correct hold rather than compensating by eyeballin it! (or Kentucky Windage!!!)
Its entirely possible to shoot slugs with reasonable accuracy outto 50 yards! More practice will produce more accuracy. Choice of ammo can impact all this too.