@surfcity you should delve deeper into your plan documents. My daughter is on a tier 3 as well ($1100 a month, of which we pay 80% after deductible), and was on a tier 2 that at one point that was $1600 per month at the age of 15. We are in the process of requesting they cover the tier 3 at the tier 2 percentages (doesn’t actually matter this year, we’re already within $500 of the maximum) because her psychiatrist deems it medically necessary. The process is the same as “prior authorization” for a drug that’s not covered (or you need to exceed their limits).
With one child hitting the maximum every year, high deductible is most favorable for us - plus if we funnel most of the cost through the HSA, we get a tax deduction for it. With the new tax code, fewer families will be eligible to claim medical expenses as an itemized deduction. It does mean those shocked looks at the pharmacy counter in January when the deductible resets (well, not anymore because our pharmacists know us by sight).