Developing flexibility as an adult can be tedious, but unless you had the foresight as a child to keep your full range of motion, then it's not exactly an option you have that's why its the first law. So quit complaining and accept the process.
Movement precedes loading. Correct movement patterns must be established before the load is added or increased. What I'm saying is if you can't perform a decent Air squat what do you think is going to happen when we add a loaded barbell to the equation?
Strength training involves using exercises that require multiple joints to move through an extensive range of motion. If you don't develop sufficient flexibility, you will not be able to perform the movements optimally; this will mean red lights in competition and an increased risk of injury. Nobody wants to get a red light on their squat because it wasn't deep enough.
"depth before dishonour."
Critical positions required before lifting.
Deep Squat Position
Squat - A deep squat position with feet flat on the floor and the spine held in neutral. This tests all of the lower body but specifically the hips and ankles.
Hip Hinge
Hip Hinge - Bend to 90 degrees at the hips while maintaining a neutral spine. I don't mind a soft knee in this test. If you want to test hamstrings individually, I prefer to lay on the floor and use a band to see if 90 degrees of flexion is achievable. This examines the hamstrings.
Laying shoulder external rotation starting position.
Laying shoulder external rotation finish position.
Laying Shoulder External Rotation - This tests the tightness of the pec minor if this is tight your going to struggle with overhead positions. Laying on the floor brace the abdominals to keep the spine neutral then allow the arms to rotate backwards until the backs of your hands touch the floor. Do not arch back to compensate for lack of shoulder mobility. If you cannot reach the floor, you should stretch the chest and anterior shoulder.
Laying overhead reach starting position.
Laying overhead reach finish position.
Laying Overhead Reach - This tests the flexibility of the lats and represents an overhead press. Lay on the floor the same as the last test except this time have your arms straight out in front of you. Now the same as before let them gently fall overhead, do not arch back beyond normal to compensate for poor flexibility. This tests the flexibility of the lats if you cannot reach the floor easily you should not perform overhead lifts as you will not be able to maintain a neutral spine position.
This is by no means a comprehensive list, but these four necessary tests will expose a lot of faults. If you fail any of them, I'd advise investigating it further as you will likely be compromising good form when lifting.
Stay Supple
J.
Law 2 - Ligaments & Tendons https://www.devanneystrength.com/articles/law-2-ligament-s-tendons-strengthen-them