The only part of US 36 that is 4-lane is the Boulder Turnpike and 28th Street between Denver and north Boulder.
If you are on I-70 in Denver and want to use US 36 on a Friday afternoon, you cannot avoid a Denver-Boulder bumper-to-bumper traffic jam. If you can figure out a way to avoid Denver and Boulder completely on a Friday afternoon, you will be considerably better off. Otherwise, you and everyone in Denver will be heading for a summer weekend in the mountains at the same time. Even early Saturday morning would be better than Friday afternoon.