Why are the burritos from Chipotle SO spicy sometimes, and other times not?

The spice you're referring to is the marinade for the meats. It all depends on the cook in the kitchen. If they're trained correctly or properly supervised, then the taste should always be the same. Also, some stores have higher standards for food quality than others.

The store my husband runs is very uniform but some others I've noticed are not.

Chipotle Too Spicy

The heat from the chipotle, which is really jalapeno that is roasted to be hotter, varies based upon when it was picked. Since they make the salsa at the restaurant, they do not have the equipment to test and adjust the spicyness. This is explained in one of the descriptions they used to give to pass the time away. It might be at the website. you might try getting a milder flavor and use the Tabasco or other condiment to spice it up to the level you want.

As in all fastfood restaurants, human beings and not machines are assembling the parts of the food. Thus, sometimes they press a little harder when having that sauce thing in your hand, sometimes a little less.

They cannot really know how spicy it got since you need only a little bit of the sauce, and any variation from the ideal amount is not easy to see.

It probably depends on who's cooking. One person might put more spice or seasoning in the food when they make it. Either way its good to me, I wouldnt mind if they added more spice to mine. lol

It depends what kind of salsa sauce you choose. Mild, medeum, or hot.

mines only spicy when i change up the salsa

It shows they dont have consistency in their products. A weakness of the company.