Replacing even a few year old parts can sometimes be frustrating at work. Ideally I want to get a bike in, assess what it needs, get it ordered if need be then crack on.
What I’m finding, especially with chainrings, is they can be a ball ache to track down. It’s alright saying go online and sort it if your at home but in the shop searching for stuff takes time, which is money…
I do my best to match stuff were possible as our place is pretty chill but other shops, I imagine, would rather just put on what they can get you from their trade accounts instead of taking time to track down a specific part to then have to pay retail for it.