The Colorado Constitution requires that all bills be read 3 times before they potentially become law. Colorado Constitution Article V Section 22 - Every bill shall be read by title when introduced, and at length on two different days in each House; provided, however, any reading at length may be dispensed with upon unanimous consent of the members present.
This goes back to early English and early American democratic traditions of reading the entire wording of all bills aloud, because there were a significant number of people that could not read. The length of bills was also a lot shorter, and the number of bills acted upon each session was very small. Today there are around 650 bills, resolutions, memorials, etc. introduced in Colorado every year, and their length and complexity has increased. Because of the increasing number of bills, the increased literacy rate and the increased length of bills today the need to read each bill in its entirety is a lot lower. However, to maintain the tradition, meet the requirements of the state constitution, and meet the need for expediency, the way bills are read has changed with time.
Each legislator has a copy of every bill and amendment they act on, so the need to read the bill is reduced. The speed with which the reader reads is regarded as a time saver in each chamber and the reading is done primarily as part of the legislative process. Unfortunately it is not done for audio or video viewers (a very recent phenomena). However, the House and Senate calendars provide the public with the bill number, short title, and sponsors for each bill, plus they can read each bill in its entirety online. The Colorado Channel also tries to provide information to the viewer within the lower-third during each meeting.
What happens on the House and Senate floor is a limited look at what the legislature does. The longer they are in the chamber the less they can meet in the standing committees where citizens have a chance to testify and where legislators can make proper adjustments to bills, based on this feedback.