We use a service that reports on our clients' PC warranty status, and we send those reports to our clients quarterly, asking whether they'd like us to renew those warranties.
Sometimes, our clients want to know my opinion on whether they should renew, so I thought I'd put my thoughts in writing.
Traditionally, an organization would extend their PC warranties to access free replacement parts and technical support from the manufacturer.
However, modern PCs have fewer moving parts than PCs from years ago; therefore, fewer parts are prone to failure. For example, modern PCs have solid-state storage instead of spinning disks, and as they create less heat, they have fewer fans. Therefore, the decision to renew hinges more on getting technical support from the manufacturer and less on getting access to free replacement parts.
If you have laptops, the argument for renewing their warranties is easier to make; they have failure-prone moving parts that desktop PCs don't, including hinges and keys, plus delicate items like screens and batteries, none of which are field-replaceable, i.e., only the manufacturer can replace them, which requires shipping the laptop to the manufacturer, during which time you're down a PC.
But, if the computers for which you're considering renewal are desktops, I'd recommend these PC longevity strategies in this order of my preference, and coincidentally, in order from highest up-front cost to highest long-term cost: