"That depends on the components. For the Power Unit, the development course is mostly dictated by the regulations. With only three PUs for the entire season, the team wants to make sure that the mileage is split relatively evenly between those three.
"Other components are driven by the specifics of the circuit. Monza, for example, typically needs a lower rear wing level than most of the other tracks. So, the team will develop the rear-wing and low-downforce package sufficiently in advance of Monza to be able to construct those pieces for the race weekend.
"For the aero programme, an outline plane will be established that says roughly when you will want to introduce new packages. It's usually spaced to a sufficient degree such that the team is confident that it will have found a decent number of gains which are then brought to the track as a package.
"However, those schedules are very fluid - mostly, because the team can never be sure precisely where the gains are going to come, how big they will be and how easy they will be to implement. Last but not least, there is also the opportunistic kind of development - where someone just has a good idea and the team decides to make it.
"So, while some update packages might have been planned for months, others updates might be brought to the car as soon as the team finds them."