Can the U. S. Supreme Court take as much time as it wants until it
renders a decision?
It is customary for the U.S. Supreme Court to try to resolve all of the case it hears in a term in the same term, but no court rule, statute, or constitutional provision compels it to do so, and sometimes it does not.
Often the U.S. Supreme Court will seek to rule quickly when failing to do so would render its decision moot (in furtherance of its capacity to legally influence an outcome). But other times it will deliberate delay deciding a pending case that is about to become moot which is called decision making via the "shadow docket."
Despite the inability of anyone to sanction the U.S. Supreme Court for delays, it is actually considerably more prompt than many lower courts (which also have more complicated tasks as more issues are pending before them in the same case simultaneously).
For example, the oldest case decided by the Colorado Court of Appeals on the completely ordinary day of August 12, 2021 was filed as an appeal in 2017, about four years earlier.
I have seen trial court motions in both the state and federal courts languish for one to two years before being ruled upon.