When I was match fishing I would spend all week preparing casters. Dividing a gallon of maggot into four, picking off the skins and dead un's then damping them down in sawdust. Once they were on the turn, there followed an intense period of riddling off three times a day, bagging up and into the fridge. On the Friday night, the lot would be ducked and the floaters skimmed off. The next step, prior to match day, was to divide the bait up in bait boxes, cover with damp newspaper, put the lid on, then into the fridge over night. That way you finished up with the best bait on the bank. After the match, what was left over, and I was unable to use, was given to someone who would. Then the cycle would begin again. As far I am concerned freezing casters is absolute sacrilege