each of the four routes is divided into six parts
we get one part per update
we are three parts in for Gabe, Ken, and Hiro
and five parts in for Mark
but some routes are divided into different paths
with Mark's route dividing on day 4 into a Mark path and a Simone/Ollie path
and Hiro's divides also into a Hiro path and an Atri path
based on narrative clues, it is safe to assume that Gabe and Ken's routes will similarly spit
we get about one part per update, and once the paths spit, it takes two, one for each path, and we get one update each two months
that means it will take 18-20 updates to finish Burrows depending on whether Gabe and/or Ken's route spit on day 4 or 5
which means it will take 36-40 months (around 3 years) to finish Burrows