Request a period that matches an honest schedule, then diarize the extension well before the approval expires. Cumulative time counts toward the five-year L-1B maximum, and a slipping project does not extend the approved period on its own.
Plan the extension on the day you plan the assignment
Two clocks run at different speeds. The project clock moves with equipment deliveries, contractors and start-up problems. The status clock moves regardless.
Treating the second as though it follows the first is the common error, and it produces a scramble in the final weeks of an approval. A better approach fixes an internal review date several months before expiry, at which the group decides whether to extend on current facts, bring Solomon home, or send a different transferee. That review is also the moment to check whether the duties have drifted into general maintenance during a stall, because an extension is judged on what is happening now.
Anyone approaching the five-year ceiling should have that conversation earlier still, since no extension is available beyond it.