Even if you assigned entries to judges in all categories, it is possible to temporarily block judging of specific categories at any time. This is useful if you have a combination of online and in-person judging. Perhaps you assign all judges to all entries, but they are only allowed to score a sub-set of entries online. You can turn off judging for the in-person categories while the judges do their work. When they arrive on-site, you can turn those categories back on.