I think that when you have returned for re-adjustment, you will find shifting greatly improved. That still depends on the rider of the bike. Even the best shifting is only as good as the "shift-er".
Remember that when you shift gears, you are physically moving the chain from one ring or cog to another. Like in stick shifting a car, that can only happen if the chain is moving. Many new cyclists expect the chain to shift by simply moving the lever. You have to ease off the pressure on the pedal while still pedaling, and wait for the chain to complete its change before resuming pedal pressure. Also consider the fact that the front shift moves more chain onto a vastly different size ring than the rear shift, so it may take 1/2 second until your chain teeth have meshed with the new chain ring.
That means practicing shifting. "Reading the road" and shifting in advance of the road codition. For example, if you see a big hill coming up, don't wait until you are on the hill, feeling resistance to get off the big chain ring. Shift in time to meet the change in hill with the right gear. (Just in case you weren't aware of the "art" of shifting).