when to cut stem

[esandyl]

Hi, need help. This is my first orchid and I have had it for several years and its been in bloom the entire time. I've repotted it once and its still growing leaves. However, there are small, looks like calcified spots on some of the leaves that are new. Also, there are 3 stems from this plant, one is really long and leggy, but it still producing flowers, it has never been without flowers and they last for months. Is there a time that the stem needs to be cut back?