What are you talking about? It took months to move the troops to the Ukraine border and when they were there they realized they need at least two times as many for any chance of successful invasion.
As for the US forces being in two places, there is zero possibility the US forces will be in Ukraine in case of a Russian invasion even if the whole rest of the world is completely peaceful at that moment.
Russia is practicing. Exercises done right professionalize the force. Units which may have never deployed with any of their current personnel have a lot to learn and that is not all in tech data. Deployment is a tactile experience. Equipment must be maintained in fit condition, packed properly, loaded safely (on everything from trucks to aircraft there are many ways to kill yourself doing it wrong), kept track of, unloaded at the right destination (FedEx, DHL and UPS keep the US global war machine running, not just Supply by a long shot), placed, tested, maintained at the deployed location, troops sustained and trained on the local operation, and that's a very short list.
The US is wonderful at deployment because we've trained on it intensively since WWII and institutional memory is precious. Knowing every inch of the receiving base before the advance team even begins is terribly valuable. Russia has a much simpler task because it can use ground transport then home station units anywhere useful within reasonable travel distance. It takes many years to get good and practice must be sustained especially with a partial conscript force (a major disadvantage of conscripts is loss rate but that didn't matter socially until the Viet Nam war era).
https://warontherocks.com/2013/12/draft ... -machines/
Russia needs many more exercises to get good but not as many to get good enough. We know Russia had a large exercise. We don't yet know their lessons learned but they will and that's what matters most. Civilians don't usually think like our military planners who must plan decades ahead. They confuse short-term circumstances with permanent realities. Russia has all the time it likes to improve while the West will shortly be distracted by something else however trivial. Our armed forces will prepare but not our politicians or public. Chinese pols and government have an enormous advantage in that respect.
Russia has our examples (REFORGER, Team Spirit) and their own in Syria. Practice deploying aircraft and combined arms is incredibly valuable and dramatically different than flying daily training sorties at home station. The US make it look easy from a distance. Up close it's an incredibly complex logistic and personnel move that is very easy to fuck up. If one loadmaster puts a vehicle or object in the wrong pallet position that can kill an aircraft sure as a SAM then not only that sortie but every subsequent sortie that bird would have flown is lost. Expensive systems are not just force multipliers, they're force loss multipliers. We see road convoy and other footage on Bellingcat etc but that doesn't convey the complexity of training, maintaining then mobilizing those units. Practice shows what malfunctions in the real world catching shit simulations may miss along with their impacts down the line.
Information wants to be free and it's more useful for the West to be relatively open about how we fight so we can be better at it. OTOH Russia gets all our lessons learned along with their own via OSINT let alone espionage.
Soldiers enjoy advanced training so most Russian players likely had good military fun. Deploying units would have equipment priority and wise commanders take advantage to improve their units. Without practice deployments they'd not know what's broken, weak or becomes that way under adversity. If Russia promotes by merit exercise can expose otherwise invisible, untested talent. It will also highlight fuckups.