Part Time employment calculations

I am looking to get some clarification on how others are calculating part time apprenticeships. 

The funding rules state:

77. If, at the beginning of the apprenticeship, the apprentice works fewer than 30 hours a week, or has a zero-hours contract, the provider must extend the expected duration of the apprenticeship, using one of the formulas below, and must work with the employer to make sure that the dates on the apprenticeship agreement and training plan are also extended: 

77.1. 12 x 30 / average weekly hours = new planned duration (months); or 52 x 30 / average weekly hours = new planned duration (weeks)

It makes no mention of changing the '12 x 30' section of the calculation for say an apprenticeship that runs 18 months it just says use one of the formulas below. 

However under the part time section for calculating off-the-job training it says: 

85. For example, for a part-time apprentice working 15 hours per week, who is following a typical 12-month apprenticeship standard, the planned duration would be extended to 24 month

Which makes me think you would change the formula based on the standard duration of the apprenticeship.

Could anyone clarify If I am correct in thinking that.

Thanks in advance 

Joe