I'm not going to lie to you and tell you it's like buying from Amazon.
When you to place an order you have to copy the link from the actual marketplace and paste it on the agents website. That's easy enough. Placing the order is also just minimally more difficult, the worst thing that can happen is that you have to top up your account instead of directly paying for the items.
Now you wait for your items to get to the warehouse. There is a chance that items are out of stock and that the seller didn't update their listing. If that's the case you wasted a bunch of time, you get your money back but not the fees. This sucks. You can avoid it by buying from specialty sellers instead of big resellers, and by confirming availability on WeChat.
But it's unlikely that your items are out of stock, what's more likely is that your items get to the warehouse just fine, where you get a chance to do an inspection via so called QC pics. You don't have to do that on Amazon, but I see that as an advantage of agent shopping because you get to do your own quality control.
Now you have to submit the items for international shipping. Even if you use our shipping calculator, you have to do some research. This takes a few minutes, but shouldn't be too difficult with all the resources available.
Once you have submitted the items for international shipping, what might happen is that you get in trouble with customs. If you did your research right, the chance is low. But this is the last factor that might be tedious, otherwise you're just waiting for your items like you would on Amazon.
The bottom line is: Yes it's more tedious, but it's manageable one you get a hang of it. There's a reason some people have spent 5 digit amounts through agents. Getting items for cheaper or items you can't normally get might just be worth it.