According to the National Conference of State Legislatures, "Legislative session length may be unrestricted, or it may be limited. Session length limitations are set in a variety of ways. The limits may be found in constitution, statute or chamber rule. They also may set indirectly by restricting the number of days for which a legislator receives compensation, per diem or mileage reimbursement."
In Colorado, state legislators meet for 120 calendar days (as opposed to legislative days, or days on which a floor session is held.) So the 120 days do include weekends, a time when lawmakers have the ability to hold meetings in their districts to discuss legislation. To view how other states manage their legislative schedules, click here.