I had a problem with splitting tomatoes & my dad said it was because I didn't water them at a similar time or too much at one time & not enough another. He said I should water as near to the same time every day & always a similar amount. He used to water in the morning & when he had had his tea & used a bucket with a jug to make sure he had given them the same amount.
Always seemed a lot of messing to me. I leave an inch space at top of the bucket they are planted in & fill with water till it reaches the top once a night & use feed once every 3 week. Seems to work.