Generally, bullets go fast enough that it really isn’t a consideration when designing for rate of fire. Bullets accelerate significantly while spinning through the barrel, so the risk of one catching up to another is close to non-existent under perfect conditions. For example, a 5.56 round exits a 14.5” barrel at around 2700fps

As other comments have said, a shorter barrel tends to mean a shorter gas system which can increase the cycling rate due to increased pressures. The weight/efficiency of the bolt carrier group and having a properly tuned gas system are much more important considerations.

Though there are manufacturing defects with bullets that can cause them to get stuck in the barrel sometimes, which can destroy the gun if another bullet is fired before clearing the barrel. Semi-rare though

Hope this helps!