Mobility routines are popular, but the evidence that general stretching prevents injuries is weak. Mobility is more useful when it addresses a specific restriction that affects your sport.
Runners need enough hip extension and ankle dorsiflexion to run without compensations; extreme flexibility is not required
Cyclists spend hours in hip flexion; time-trial and aero positions require good hip and thoracic mobility
Strength training through a full range of motion can improve flexibility about as well as stretching in some studies
Short, regular sessions are more realistic than long, occasional ones
A ten-minute routine that covers most endurance athletes: half-kneeling hip flexor stretch, knee-to-wall ankle mobilisation, thoracic rotations on all fours, deep squat hold, and a hamstring floss. One or two sets, gently, a few times a week.