S.Res.479 - An original resolution amending the Rules of Procedure and Practice in the Senate when sitting on impeachment trials.
https://www.congress.gov/bill/99th-congress/senate-resolution/479
Amends the Rules of Procedure and Practice in the Senate When Sitting on Impeachment Trials to make various technical and procedural changes, including: (1) that an article of impeachment shall not be divisible for the purpose of voting at any time during the trial; and (2) that once voting has commenced on an article of impeachment, it shall continue until completed unless the Senate adjourns for one day or less or adjourns sine die.
Clinton impeachment trial took about a month. Legislative and other businesss took place in that time period too.