If volume/performance is a concern, it’s definitely better to isolate validation functionality into a single client side script if possible. This improves performance and allows you to more tightly control the logic within the script. Maintainance wise, make sure to use lots of functions to separate out logic. Governance wise, I believe the limit is 10 client side scripts deployed to a single record - worth noting that you want to make sure not to overload a single script to exceed the 1000 point usage limit.