I am not qualified to judge whether stronger winds tend to make for longer holds. I would bow the the greater knowledge of an IR instructor, and probably more to the point, to the (undoubtedly more important) requirements of an IR examiner.
As for the varying bank angle, holds are based on rate 1 turns, and are usually flown at around 210 knots. This conveniently requires a 30 degree bank angle. It is only when flying at other speeds that a different bank angle is needed. 18 degrees of bank is required at 120 kts, whereas a fraction under 35 degrees would be required if a rate 1 turn were to be flown at 250 kts.