Posting up

Should the front leg lock, stay bent or slightly flexed during the release point. I noticed many pitchers post up during the follow through or upon releasing the pitch. There are many different degrees of it though, and I’m not sure which is correct, however I have posted my mechanics under the mechanics section and you can see that I stiffen up my leg at release point but mantain a little flex until follow through. Is this correct?

you need to plant on a bent front leg. What happens after that (i.e. whether the leg locks and when) is usually different from pitcher to pitcher.