Join Multiple combines more than two input streams. Choose the join fields for each input and decide whether the result should include records that appear in every input or also preserve incomplete matches. Each source needs an agreed grain. Matching on Worker won't produce one row per worker if a source contains several rows for the same worker.
The all-input setting is useful when a report needs a complete HR, payroll and band assignment record. Missing band assignments then need a separate investigation, because their absence from the result is a consequence of the rule. Duplicate matches can multiply across all inputs, just as they do in a two-input Join. Check counts and retained source fields so you can explain which record each value came from.