One issue is the differentiation between the Income Statement approach and the Balancing Sheet approach.
Students have an opportunity to deal with a fractional percentage.
This is simple for some students, not so for many more. You have to consider the present balance under BOTH approaches. While it is usually zero under the Expense approach because interim entries have not been made, real companies could have such a balance. An adjusting journal entry will result under BOTH approaches. South-Western College Publishing.