It sets the outer boundary of the plan. Maximum stay in L-1B status is five years, and any time already spent in the United States for the group counts toward it. A three-year assignment plus a two-year extension exhausts the allowance, so the question of what follows should be settled at the start.
Plan the exit before the first admission is granted
Assignments that were meant to end rarely do, and the five-year ceiling arrives without warning if nobody has been counting. Félix should have a record from the outset of every day spent in the United States for the group, including short commissioning trips that predate this assignment, because those days are not free. Around that ceiling sit several sequencing decisions.
If his role is likely to become genuinely managerial as the American operation grows, the different ceiling attaching to L-1A is relevant, though the category is decided on duties rather than on convenience and a change is not automatic. If the family intends to remain, immigrant categories with their own requirements would have to be examined well before the fifth year, since eligibility and visa availability are not things that can be arranged quickly. And if the yards want him for a fourth and fifth year of maintenance work, the honest question is whether that later work is still specialised knowledge or has become ordinary service delivery.