I'll add some backround to this need to trim the ft der cage to eliminate rub after shifting.

Back in the day this trimming was done by one's hands, the shift lever would be nudged one way or the other to position the cage centrally WRT the chain. And we called it "trimming" When indexed systems came onto the market the shifters were still using a friction function for the ft der. So ft trimming was still a manual function. With the advent of STI (brifters) the ft trimming was built into the shifter, still needing a manual step but the amount of corrective trim was programed by the shifter internals. To offer STI controls at lower price points (Remember Shimano is famous for their market plan of introducing their newest features at the upper groups first) they eliminated some of the shifter's complexity. So some of all the trim features went missing. Shimano has learned better that trim features is a wanted thing at nearly all price points and has trickled down this feature to lower cost groups as time goes on.

Interestingly is that early on in the MtB indexing systems Shimano provided a small instructional sheet (pictural in it's layout) describing the cog and ring combos that might have some rub. Very few people ever saw this slip of paper that came with the new bike's paperwork. I have never liked the industry preference to not provide operational instructions for their products, this is on both the manufactures and the LBS people. Many shops would toss all but the owner's manual when assembling the bike. Rant over. Andy