"This is what I think pausing your Tamagotchi does:
Let's just say I hatched my Tamagotchi at 8am this morning. So it evolves into a child at 9am. We all know that a child evolves into a teenager 24 hours later, right? So it should evolve at 9am the next day.
But then I have to pause my Tamagotchi for another three hours. The next day, instead of evolving at 9am, my Tamagotchi evolves at 12pm.
Mind you that is what I THINK it does. It doesn't really slow it down, as in staying in the child stage for say 30 unpaused hours. Basically to get a Tamagotchi to evolve it has to stay off pause for a certain amount of hours. That's just my theory though.
I also believe putting a Tamagotchi to sleep can stunt the evolution process, as a Tamagotchi can't evolve but can age during its extended sleep. " - dancinkayley
dancinkayley is another user on TamaTalk, and this is what he/she said on another post. All credits go to dancinkayley!
Hope you found this useful!
Tomodatchi_Lovely