One must always keep in mind that the Bible uses numbers for shorthand. Forty years or Forty days or Four Hundred xxx = 4*10*x.
10 signifies divine completeness. 4 signifies god's creative works. Thus, 40 signifies the creative completeness of god's works. 40 is also the product of 5 & 8 and signifies god's grace manifest, ie, the completeness of the probationary period. 5 = grace; 8 = renewal or revival.
See E.W. Bullinger, "Number in Scripture".
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'.