It is offered when your IEP requires it. However, I have rarely seen "individual instruction by a special ed teacher" in an IEP, except for autistic students in certain out-of-district schools.
Do not confuse appropriate and restrictive - sometimes appropriate requires more intense instruction.
The "least restrictive" requirement is more to protect your child from being placed in a segregated or non-participatory setting when the school should not do so against your desire. When YOU desire more intense instruction, that is not held against you. However, the school must agree to it, and it is a very expensive option to use 1/6 or so of a highly-paid special ed teacher's time to offer private instruction to a single student for a single period, and to pay 80-90 thousand a year for one to privately instruct your student (including benefits) is almost unheard of (without a fight from the school for sure).
This should not be considered legal advice and is intended for educational purposes only. It does not constitute a contract for legal services between any parties. Answers are given to questions for which there may be additional facts not mentioned which might change the legal issues or consequences.
I would agree with Mr. Popovich that (understandably) you may be confusing different concepts. I see LRE and FAPE (Free Appropriate Public Education) confused all the time - often by educational personnel. LRE refers to the least restrictive environment for your child's needs where appropriate services can be given. School Districts with budgetary concerns like to group "like" students in a given class so that they can better use of the teacher for that class.
The law requires that where a student can be given those services in a less restrictive environment using "support services" (e.g. one-on-one aides, assistive technology, pull-out speech therapy) versus a self-contained classroom, then that is to be given preference over the latter. The fight develops where the parents and schools disagree as to what are the "appropriate" services and what is the LRE for the student in question.