I won't say what you should or should not do regarding feeding. I have a few colubrids that I grew more slowly than what would be considered more common for captivity growth. All are extremely healthy. The few that I did breed had no trouble at all laying eggs. IMO slow growth is not a problem in any way as long as the snake functions normally and is not being starved.

In the wild, slow growth could mean the snake is at risk of predation for a longer time. That is why baby snakes will eat all thru winter in captivity if allowed to - the instinct is to eat and grow quickly.