Network Engineers of Reddit: What do you look for when optimizing your network?

Hello, all. I just started my first job as a Network Administrator for a mid-sized business. The current infrastructure is primarily Cisco devices and follows the traditional three-tiered network architecture. I am curious about what some of you more seasoned network veterans do in order to find areas of improvement within your network space. What kind of event monitoring do you have in place, and what events are you looking for? When designing your network, what kind of protections do you put in place for unforeseen issues that may crop up on your network (aside from full mesh redundancy, I have a budget to adhere to.) What tools and experiences can you share regarding network-wide monitoring and ways you improved your network without over-spending?

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