Everything has a life cycle and how they last depends on a number of things, but heavy traffic and transports will cause life to be a lot shorter.
Concrete roads stand up a lot better and longer than asphalt roads at a greater cost as well longer to (re)building it.
Safety is the number 1 cause for slower driving as well having less lanes to use for travel. Regardless of all safety measures in place, you will still have ass hole drivers thinking they are god and care shit for the workers on theses projects or the drivers who obey the rule who end up causing traffic mess, injuries or death in the wake, including their own or people in their vehicles.
How traffic was looked at decades ago to having x lanes down the road, under estimated the amount of land needed for an ROW as well lanes to the point you need to look a razzing areas to widening the road or interchanges. A fair number of interchanges where poorly plan that they cause backup of traffic even in the off peak time. To rebuild some of them may require closing parts of it for a number of years creating a greater backup for other interchanges as well the side roads to get around the closure.
QEW was the first hwy built, but not enough ROW was put a side in Mississauga to widen it today, other than double deck it or remove service roads as well all structures along it. It would cut off east-west travel route that exist today since Mississauga road system was poorly layout in the first place. There are other places along the QEW with a narrow ROW as well to meet future expansion. It also applies to other roads in Canada as well.
The old guardrail between lanes became a safety issues that they were replace by concrete barriers that were too low that allow vehicles to climb them in accidents that cause more damage in the on coming lanes. Even rebuilding those barriers to be higher as still too low like the US where their barriers block the headlights of on coming traffic and harder for vehicles to get into the on coming lanes from my point of view.
Until there is a true transit system that is faster and offer better service today as well get people to where they want to go in the first place, gridlock and construction is the fact of life along being stressful to drive.
There are only certain company's that can do highway work as well manpower to the point that things will move slowly and longer to get things built or rebuilt and subject to funding them.