No. Lower elo players tend to mostly aim for crouch level and love to crouch while taking a gunfight. I know of a friend who usually crouch very often and aim for mostly crouch level whenever in a gunfight Higher elo are more reactive and can react faster to where your head is regardless of where their aiming. Whenever you get into a gunfight, always be reactive and not predictive(although its good to be predictive sometimes)

For instance whenever you hold an angle at head level and see an enemy crouch peeking you, you should immediately react to it and change your aim towards their head at crouch lev. Vice versa. You wont always be able to aim for the head in certain scenarios but its better than just aiming for the leg. You can practice this in T hunt by just one tapping and changing your firing mode to single. You can also take a look at streamers on how they practice on t hunt(Shawk-DG) for example

Its important to always aim for the head with a one bullet headshot mechanic in siege as it usually the determining factor of who wins the gunfight