Student or Learner
The person shall perform its services as expeditiously as is consistent with such skill.
What is the subject of is; Is it the person?
That sentence is incorrect. The closest correct form would be, "The person shall perform their services expeditiously, as is consistent with such skill." One could also say, "The person shall perform their services as expeditiously as would be expected from such skill" or something like that.
PS: The use of the word "person" is unnatural here; I can understand why you would use it here, but I would like to make sure that you know that one would say "he/she/they" or specify the person's name or role.
[Not a teacher]
Thank you, guys.
The sentence is correct 100% and I only switched the subject person from other professional name--if it helps clarify the use of its.
Then, who or what is consistent with the skill? Can you tell me more clearly than vaguely?
Perhaps you can rephrase it as below:
Mr. X shall perform the services as expeditiously as required by the skills.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.