Count the ceiling from the first day in the classification, not from the current petition. Keep travel records so that time spent outside the United States can be recaptured. Decide at the outset whether the assignment ends at five years, whether the role is expected to grow into a managerial one, or whether an immigrant route will be considered.
Three plausible endings, chosen early rather than discovered late
The classification allows a maximum of five years and no extension beyond it, so every renewal spends part of a fixed allowance. The first ending is a clean one: the assignment is scoped to finish inside the limit, the knowledge has been transferred to American colleagues, and the transferee returns. The second involves genuine change: the role develops into managing people or an essential function, and a different classification with a longer ceiling may become appropriate, but only if the duties really changed and the record shows when.
The third is an immigrant petition, which takes its own time and cannot sensibly be started in the final months. Recapture of time spent abroad is a real benefit and depends entirely on evidence, which is why boarding passes and passport stamps should be filed as they accumulate.