Can we adjust our server’s Max Execution Time?
Answer: No. We keep the recommended default of 30 seconds for max execution of any PHP scripts. This is more than enough for properly coded scripts, especially the type that are used in a WordPress environment.
If your plugin or theme is displaying a “warning” that max execution time is not enough, it is likely not coded very well.
Modern javascript code and AJAX queries can easily work “around” any PHP timeout issues:
Above and Beyond: Avoiding PHP Timeout and Memory Limit Errors with Ajax