Two tasks assigned to one person at the same time can each look reasonable in isolation. The conflict is their combined demand on that person's available hours. A revised chart needs to show how that conflict was handled, not merely stop displaying a warning.

Use an automatically scheduled practice plan in Project desktop for Windows. Give one fictional full-time resource two independent four-hour tasks, both initially starting at 08:00 on a day with eight available working hours. Their total is eight hours, but both require the same person during the first four hours.

Record the rules before leveling

Open Resource, Leveling Options. Project resolves overallocations by delaying or splitting tasks according to these settings. Use Manual for the trial and inspect the detection interval, date range and leveling order. Hourly detection can expose a conflict hidden by a coarser daily or weekly total; the chosen interval matters.

Record the task starts, finishes and assignments before running Level All. In this example, simply placing the four-hour tasks sequentially could fit the eight-hour day if all other conditions permit. The model has not acquired a second person just because the two bars no longer overlap.

Level only within available slack limits finish-date movement and may leave conflicts unresolved. The splits option permits interruptions in remaining work. Review the result using View, Gantt Chart, More Views, Leveling Gantt. Inspect which task moved or split and whether the project finish changed.

Judge the proposed sequence operationally

Compare the proposed allocation with the original eight-hour capacity. Check whether an interruption is acceptable for the particular work and whether the delayed task still meets its actual requirement. A mathematically nonoverlapping arrangement can be impractical if work cannot be paused midway.

Clear Leveling removes leveling delays and leveling-created splits, but it is not a general undo for all schedule edits. Microsoft documents an exception where a previously leveled task is later given priority 1000: clearing does not remove that task's leveling delay or split. Retain the untouched trial copy for comparison.

Before applying a result to an operational plan, record the chosen options and the unresolved conflicts, if any. Accept the new sequence only after reviewing its timing and interruption assumptions. Leveling changes when existing capacity is used; the staffing decision still needs to be made by people who understand the work.

Sources: Microsoft: resource leveling.