If the shifter doesn't say "double" under "105" and "Flight Deck" then it may be the triple shifter and it can be excessively stiff (and self-destruct) if adjusted wrong. I've done it. That said, even when properly set up it'll still feel harsher than a flat-bar shifter like you're used to. A big part of that is that you're shifting through all the trim positions at once, which is another reason why you'll notice more clicks than you have gears even if you have the double-specific shifter. That's just the way road shifters feel.

Easy test to see if it's adjusted wrong enough to damage the shifter (regardless of model):

1) Shift into the big ring to the highest click the shifter will go to.

2) pull on the front shifter cable under the downtube (if it's exposed) or push the shifter again as if you were upshifting (don't push hard)

If pulling the cable/shifter causes the front derailleur to move a tiny bit before hitting it's limit then it's not too tight. If the derailleur doesn't move at all then either the limit screw or the cable needs to be loosened because there's no slack at all, which puts extra stress on the shifter mechanism when you downshift.

You want it to just barely move. That ensures the tension isn't too high without risking the chain falling off to the outside of the chainring.

The trick to set up is making sure that you have that tiny (minimal) amount of slack above the shifter's highest click/position. If the shifter has an extra unused click on the high side then as the cabling loosens up over time it becomes possible to force the shifter into that higher position where the cable is way too tight, over-stressing the shifter. That can't happen if you make sure to use the highest click from the beginning since the cables can only get looser, not tighter, with wear.

No offense dude, but they certainly know their stuff better than you do right now. They build bikes and know how the shifting should feel.