$0 Deduct Comprehensive Insurance- a good deal

I have always carried a comprehensive deductible of $500 or so on my cars, thinking that this is the way to go. In the past couple of years, Ive had 3 incidents that required glass replacement for my '01 Blazer. I never really thought much about the insurance cost until recently as 2 out of the 3 replacements were below the $500 deductible. Someone broke the back window out of the Blazer and I was getting bids north of $1000 to replace. So I called my insurance agent to place a claim. While I was on the phone, I casually asked what the difference in price would be had I just had $0 deductible. The agent made a quick calculation and told me it was around $16 every 6 months. In complete disbelief, I hung up to ponder this one!! A quick calculation showed me that it would take me more than 16 years of paying this added premium to spend that $500 deductible. I was not happy.
I called the agent back to complain that they should have instructed me on this. I am a long-standing customer and why wasn't I provided service that would have brought this to my attention. Long story short, they back dated my policy in order for me to recover the $500 deductible. But I'm still out for the other two glass replacements!! So, if you've not checked recently on your comprehensive coverage and you are at a high deductible, make sure you ask you agent what the cost difference would be. I think you'll be surprised.