You've been running them on EXMARK for some time so I thought who better to ask. 1. When is the best time to run doubles? When not to? 2. What are the blade that you run & which do you place on top. 3. Do you placw a felt washer between the 2 to eleviate slippage? Everyone else is welcome, not trying to exclude but I've seen John's Pics and they are goood.