Does a return of premium life insurance policy make sense if you compare it to permanent life insurance?
No. If you cancel your return premium term life insurance before the 20 or 30 year term is up, you get nothing back. You only get a return of premium if you outlive the term of your return premium policy, and keep the coverage "In Force" through the entire term.
If you want permanent life insurance coverage, and you're willing to pay the extra for it, buy it up front. Most people, "buy term invest the difference" of the cost between a permanent life insurance policy and term life insurance.
Any life insurance with a savings component to it - including return of premium term - is going to make way more money for the insurance company (and the agent) than it will for you.
RUN THE NUMBERS. Compare the extra cost for the "savings" value of your life insurance, to what you can do with the money yourself if you invested it.
Here's how you can learn more about return premium term life insurance and how it works.