I have found that quite often the quality of experience depends on the location as well as the company. I have never had a problem with Alamo 3/4x promos being applied the same (or the next) day as my return in LAS. In the past year I must have used Alamo 6 times, and 4 of the 6 I was able to use a multi code. The only time I did not use a code, I found a better rate over a holiday week without the code.

However, YMMV.