Legion of Kittens Mom's Box
"One thing I think is not widely known, is that Mom's box has a pity timer. This means that the longer you go without pulling a "good" item, the greater your odds become that you will. Once you do get a higher end item the odds will reset back to the base value. The pity timer is NOT affected by Mom's box price reset or jackpot prize change.
"...The pity mechanic is an automated part of the loot odds that increases every time you don't get a top item. It's just there to help if you go for a long time without a good pull. It exists in thousands of games and in many, many instances it's not even player-facing information. I'm waiting for info to find out if the pity timer involves ANY top tier item or just the jackpot."
- ModchiKopi, March 20, 2018
"The pity timer only resets when you get the Jackpot prize."In some ways I regret sharing the info because I know it's especially frustrating for those who have run into a bout of bad luck. All I can say is, the pity timer does indeed increase your odds to get the jackpot every time you don't get it, but it is still RNG with its own pitfalls and frustrations."- ModchiKopi, March 21, 2018
ModchiKopi is Animation Throwdown's player relations associate & forum moderator.
These excerpts were taken from http://www.kongregate.com/forums/727066-general/topics/1580185-official-mom-s-box-jackpot-rotation