Does Claude feel different to you day to day or am I the problem?

A user on reddit.com's dev_community forum observes that Claude's performance varies significantly day-to-day, even with similar prompts and tasks. Some days, Claude perfectly executes copy work, matching tone and length on the first try. Other days, the user struggles with Claude misreading tasks, being overly formal or structured, and requiring extensive over-explanation. The user questions whether this inconsistency stems from changes in the model or their own prompting style.