In the movies, we often see a Roman soldier standing alone, dueling it out with some large fur-draped barbarian. The Roman eventually fells with a single telling thrust or slash. For example, see the opening combat scenes of the movie Gladiator.
Actually, Romans fought more as a unit, a team, unless their ranks were broken. They battled with shields close together, maintaining a three-foot fighting space on each side of them — and they often the fought even closer together, especially when a shield wall was needed to repel a frontal attack! And the dramatic full fatal thrust was rarely done (e.g. the blade emerging from the back of the opponent.) Such an “overreach” could put the legionary in harm’s way.
Public domain image via WikiMedia Commons. Ernst Wallis author.
For the Romans, a series of short stabs was the key to felling enemies. The Romans knew that several stabs to the abdomen (a preferred target because it was easier to reach without exposing oneself) could: 1) send an opponent to the back lines, 2) bleed them out, thus weakening them for a fatal blow if they didn’t die first, or 3) eventually kill their opponent through infection. As the historian Vegetius notes:
“A stab, though it penetrates but two inches, is generally fatal.” Vegetius, De Re Militari. Book I.
This doesn’t mean that Romans always stabbed at their opponents’ stomachs. Like any efficient killer, the Roman legionary was opportunistic: they would slash or chop at whatever exposed body part they could reach with minimal risk.
“However, the gladius in some circumstances was used for cutting or slashing, as is indicated by Livy’s account of the Macedonian Wars, wherein the Macedonian soldiers were horrified to see dismembered bodies.” https://en.wikipedia.org/wiki/Gladius
Scipio Africanus’ Gladius Hispaniesis was deadly effective because it allowed Scipio’s soldiers to stab, slash, or chop with equal alacrity (see The Three Generals, or Scipio’s Dream). The legionary did not have to overpower their foe as much as they had to score points on them with a well placed thrust or cut. Time was their ally in most battles, along with their legendary discipline and organization.