My very uninformed opinion, as a volunteer at cat rescue. We have had a few cats taken into foster care for longer periods (month or more) who have benefited in overcoming their fearful behavior. I don't think a weekend would be of benefit. Possible exception might be if cat has been surrendered from a stable home (we have a number of pets surrendered by seniors who can no longer care for them) but these cats are not usually long termers, or are popular foster care candidates as they are low maintenance.
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