Depends which one and why. Say if it is the Vyazma-Bryansk pocket in October because Hitler opts not to launch Typhoon and goes on the defensive. That may not necessarily turn out to shorten anything, though it saves about 1 million Soviet troops. They probably get frittered away over the winter and don't wear the Germans down nearly as much as the OTL winter counter offensive, nor put them in a precarious spot, while the Germans then have time to get ready for winter and get their logistics in order. If it is any of the earlier pockets, then that could derail all the others and change the entire course of the 1941 campaign, so you need a good reason why they don't happen so we could figure out how things would play out from there. Ultimately there can be no generic answer as the specifics of why and which pockets are avoided changes things differently throughout the course of the war.
Well, Bialystok is nigh impossible to save. But Minsk is distant enough to be saved.
All the other encirclements are far enough away in distance from the Curzon Line and far enough in time from June 22 that different movements could have allowed the Soviets to avoid the encirclement, or break out.
For example, maybe the Soviets could have baited the Germans into getting stuck in Pripyet Marshes by maneuvering their line and retreating in such a way that there was an obvious (contrived) "vulnerable" point at the western end of the marshes, encouraging the Germans to attack into them, while Soviets reallocate their forces to the north and south sides of the marshes. While Bialystok-Minsk would be doomed (this would probably be an extension of retreating Soviet forces from the area between Bialystok and Minsk, retreating back into the marshes), this might slow down Army Group Center enough that the other encirclements by Army Group Center would be prevented or preventable.
That aside, Smolensk is definitely preventable, it's not even in Belarus but in Russia, so different movements, Soviets holding the surrounding roads and rail a bit longer, or an early retreat could lead to Soviet forces saving their forces from the area.
The Romanians had minimal armor and the Germans took a while to actually advance in Ukraine. So if Army Group South gets slowed down in pretty much any way, the Kiev encirclement can be prevented.