Depends on the fighter and how much he has to cut to make weight everytime
For example, a guy like Montiel cannot stay around his weight class all your round
Also consistanly working the body all year round can also take its toll
They have lives outside of boxing. They need to have fun and eat food they like. Plus with a good nutrition & fitness coach, you can get in fighting shape in 2-3 months.
it depends on the athlete as many of the top guys per weight division are enormous for their given weight class. it's fine to be at 6-8% body fat on the evening of a fight, but not all year round.
but yes, i do believe they should at least be at a good fitness level throughout the year, it's literally their profession for goodness sake.
They should be allowed to relax.. I mean, who really wants to train hard all year long?
But by relaxing I don't mean ballooning up to 500% of your fighting weight a la Hatton..