From the other side
We never let a chair go empty because of slow scanning. At each of our scanning lifts, we'll have 3-5 scanners, depending on the crowd. We have discretion on when to scan to a certain point. We'll get everyone at least once. If something stands out about you that we remember, you may or may not get scanned again. We'll scan ski school the first time they come through, then only rescan if the instructor picks up new clients.
Now, some issues from the scanner side:
I can't stand it when people saunter up to me and don't have their passes/tickets ready. They spend time fishing it out of their pockets or zipping down 4 layers of clothes to get the passes. I mean, come on, you had all that time in the line to get ready. As long as I can see the ticket, I'll grab it and scan it as fast as I can and get you on your way. When things are going well, I can get you scanned in a second (literally). If you've fallen and have snow on your ticket, I might have to take an extra second or two to clear the snow off of the barcode to scan.
Plastic pass holders. Sorry, MSL. I really don't like them. They cause all sorts of headaches for us. Different thickness, different clarity, different pliability - it all has it's impact on the ability of the laser scanner to accurately go though it and capture the barcode. And, if you get any condensation in there, forget it. If it's dirty, it isn't going to scan quickly. If you have it placed where the entire barcode isn't visible, it isn't gonna scan. Some of the holders built into jackets just aren't that easy for us to get to for scanning, either. The ones that pull out are usually the best. The ones built-into the zipper part of the jacket are nightmares - it's a contortion act for us to scan them. The ones on the arms are not nice, either. They are usually have crinkled plastic and the laser bounces off of them instead of going through. The DC jackets have the worst - their sleeve holders have a large "DC" logo on it, making it impossible to scan. One of the best ideas I've seen with the plastic holders is when people cut out the part of the plastic where the barcode is. That way, we can get directly to the barcode to scan.
Passes on helmets. I actually like this. People attach their passes to the goggles holder on their helmets or wrap it around the goggles themselves. The goggle strap holds the pass in place while you ski. I'll grab it, scan it, and put it back under your strap. Just don't be 7 ft. tall and try this...
It's our job. I know I take pride in how fast I can get someone scanned and on through the lift line. But, it takes a little bit on the guests' parts, too, to have a fast scanning process.
I go out of my way to find jackets with pass holders, currently have one in which the pass flips down from the hem and can be tucked away afterward with one sweep, with mittens, no zippers involved. With scanning, pass will NOT scan through the clear plastic cover of the pass holder, rendering it useless. Hate having a "dangling" pass, have recovered too many in the snow. (including DH's)
The scanners that we use here work best if we can get about 6 inches between the pass and the scanner. I'll get into a rhythm where my arms just get the right distance and angle the pass just the right angle to scan. 
