Do you have to precommmit to the grocery store with how much candy you'll buy? If not, then really the only added complexity would be the label printing step - you just print some labels on different frequencies from others. If I were you, I'd be listening carefully to the feedback you're hearing in these comments - seems like there's a lot of demand for a less frequent/less expensive option.

If you want more data on whether you should do this, try asking customers that have canceled their subscription if they'd stay on if it was once a month. Also, think about running an a/b test with once a month vs twice a month...

No, I don't need to precommit. There is nothing really preventing me from doing this.

I want to say yes to this experiment, but immediately come up with more stuff that this would require that holds me back from adding it right now.

With tiers you will eventually have people who want to upgrade / downgrade between the tiers (of course I can just say you can't do that). I need to change my scripts that scan PayPal to support these tiers and still correctly figure out who to send to.

Need a tier selection page and this will also complicate wording on the main page. Not missing out on those customers who only wanted one envelope a month seems it might make this worth doing, agreeing with you there and hoping to find the time to add this.

I agree, I don't think your churn rate is so bad that you need to offer any more levels. I would put all your work into acquiring new subscribers first. Every business is going to have churn, but the only way to grow is with new customers.