A previous change in Pokemon GO has been removed. A while back, Niantic Labs updated the whole gym training mechanic. Specifically, they made it quite a bit harder to level your own team’s gym. It took literally twice as long as before. This made it nearly impossible to hold a gym for very long. Luckily, it’s back to normal now.
The change back comes as a relief to the Pokemon GO community. When training a gym was twice as hard, it only increased the chaos of gym management. Even on the best terms, gyms can swap multiple times during the week. So now, gym training is back to normal and is a viable part of the game again.