Sounds like you have a questionable routine. With the rep set scheme you are on you will be on a short road to injury. 27 reps?? I can't think of any press that I would do 27 reps on. You are only fatiguing your supporting muscle groups, which help to stabilize joints. After that happens, if you try a heavy weight with poor form, you can mess yourself up easily. And tendon/joint damage take an eternity to heal.
Get a good book on training principals and get on a real program.