I also have a Companion Bible, which has his appendices & notes.
40 is also significant of "probation".
However, the 40 years in the beginning of my post was what I referenced from the post I was answering. I posted the Biblical quotation to dispel the two common misconceptions in the post I was answering:
1) The Israelites literally "wandered" for 40 years. They didn't; they spent some extended periods encamped in various places;
and especially,
2) That the pillar of fire/cloud was "always" before them. It wasn't, as when they were encamped, 'the cloud abode upon the Tabernacle'.
"However, the 40 years in the beginning of my post"
I justed used it for the opportunity to point out that numerology plays a significant part in oriental literature.