A few years ago my corporate travel policy was "cheapest available ticket, no ifs or buts". Most of my itineraries were 10+sectors, 3 or 4 airlines, 2 or 3 tickets. I tried to argue that given the structure of my travel, there were too many weak points in the itineraries for the policy to be sensible, but "the policy is there for a reason, stick to it" was the message back. Time and again something happened on route: a delay on one flight leads to missing the next on a different airline so the missed flight required rebooking; a customer changed the meeting, time for a new ticket. I would say that in a 12 month period I ended up paying three to four times the original itinerary price, and each trip had 5 or 6 re-routes or date/time changes. The policy never changed and I got told off for not planning my travel better...
Fast forward to today, same travel routes and structure, same number of changes, before and after the ticket is issued. I don't buy full fare tickets, but in the last 12 months I don't think I have paid more than GBP1000 in changes for 50k odd spend.