I was wondering if it's possible to execute system commands without saying 'System Call'. The anime series Sword Art Online: Alicization shows something like that but I was wondering if the characters really didn't say 'System Call' or it was just obviated and not shown to the spectators. In Chapter 21:
Kirito is fighting with Eugeo when he said: 'Burst Element' generating a powerful wind burst. But he didn't say 'System Call' nor 'Generate Aerial Element'.
Also, The Administrator healed the wounds of Eugeo without saying anything. In addition, she blocked Eugeo's attacks with a magical shield without saying any command.
I was wondering if both characters used the proper commands to cast magic but it wasn't shown to the spectators or in-universe, they didn't say anything.
Maybe they are so powerful that they no longer need to call the system using 'System Call', they just use telepathy or something like that due to their high authority level or a previous secret command? Or maybe the command was just skipped by the director of the anime?
Is there any clue about this on the manga or the novel? Anything? I love spoilers.