Google Apps Script is an amazing language that can automate a lot of your work. However, working with GAS also means that you have to learn to live with its built-in limitations and quotas. One such quota is the total script runtime. … I have experienced that the time required to complete tasks like copying or even simply listing files on a drive or in a directory can be quite long. Merging hundreds or thousands of documents can also take longer than both thresholds. Now let’s look into how we can build a solution
Another community contribution looking at handling script runtime and this one is also worth looking into for tips on structuring your code. The tutorial includes lots of useful information and an explanation of what is going on and might be a useful example to look if you are interested in moving your Apps Script coding abilities to the next level.
Source: Bypassing the Maximum Script Runtime in Google Apps Script
Member of Google Developers Experts Program for Google Workspace (Google Apps Script) and interested in supporting Google Workspace Devs.