Most fighters and their coaches cater their training and strategy to best increase their change of defeating their opposition. Many boxing trainers also spend a considerable amount of time watching videos, fishing for a tell that they might be able to take an advantage of.
Some fighters on the other hand, have had enough time in the ring to let their experience and ring IQ guide them in the right direction. From the first bell they feel out their opponent, while their corner is looking for flaws and repetitions.
For Floyd Mayweather Jr., who claims that he never takes the time to review the tapes, leaving it to his trainer, a bout against Manny Pacquiao might be a good reason to get more involved.