It all depends on water depth and your subsea equipment limits (the angle between the flex joint and BOP being critical). If you don’t have it within acceptable limits then they can key-seat the inside of your stack when your drilling, which is very very bad. Past very, very, bad.
Make sure you know the limits down there and any guidance on safety factors, but 20 feet of offset in 3,000 feet of water is only 0.38 of a degree down there. I’ve been conditioned by different parameters in dynamic positioning, but 20 feet is not so bad for normal drilling activities on that sort of water depth.
All of that being said, many clients will have more conservative ‘artificial’ limits and you will need to go by these potentially much lower limits depending on the company operating the rig and/or the client.