Depends how much time you have, how much you need the money and how cheaply you can do it.
Eg if you can walk to the lockers (make sure they're the right lockers for the postage service you offer), have packaging you can reuse, have the time and could use the money, then you might as well.
If one or more of those don't apply, it will start to feel like more hassle than it's worth, especially the time/money aspects.
I've sold a bit on Vinted, can walk to most of the lockers etc, and indeed it's a good excuse to get out of the house and go for a walk but am also time poor and disorganised so only really sold things I knew I could get at least £5/10 for.
When I had a clear out I put aside a pile of items that collectively got me about £150, so felt like it was worth it. But it wouldn't have if those same 20 items only got me £20/30 for the same amount of packing up and running around so they went in the clothing bin at the recycling centre - I'm a big fan of those because they're sorted by people who know what is worth selling to rewear with the rest being shredded for insulation etc so everything is appropriately dealt with.