Adding multiple exposures (subs) to create a single image is one of the key elements of doing astrophotography. It enables us to get rid of bad pixels, satellite trails, noise while increasing signal to increase the overall signal-to-noise ratio. It truly is one of the most important aspects of astrophotography.

Basics of Stacking - Lightframes, Darkframes and Biasframes

The benefits of adding more subs to your stack

The most important conclusion is that stacking frames will benefit the final result not just in terms of Noise, but also in terms of Dynamic range. Keep this in mind!

The noise cancellation has a clearly visible diminishing return after around 25 frames. Aim for this number of frames as a minimum in your stack. Increase exposure time appropriately if you know for sure you are going to get 25 subs.