I have Shimano SL-4700 Tiagra (flat handle) Double shifters. However the front shifter has 4 positions in this order:
As can be seen in the image below.
However, I can't make sense of how this is meant to work because there is no way to move between the untrimmed settings. For example, if I want to jump to the small cog from the big cog (from H to L), I would expect to simply pull the top lever with my finger, but in fact it just goes down to the Low Trimmed so I have to do a second pull.
Furthermore, one of the trims has little effect anyway, and I find trim useless anyway as I never cross chain. I'm wondering if Shimano intends you to only use 3 of the settings (i.e. (1) H/HT + L, or (2) H + LT/L) by judicious setting of the limit screws, but I can't find any info about this. My old 8 speed Claris had only one trim, which I could bypass when changing. Not being able to go from high to low with one input seems weird, and I can't imagine Shimano would design the system like this.
Finally, when adjusting the cable tension and limit screws is there any special technique to deal with the trim.