Will visitors of eshop benefit from "Next product" and "Previous product" buttons on product detail page (just buttons, so they are basicaly getting random product from same category), even they can choose another product from "Similiar products" section close below? Client has it on his current eshop that I'm redesigning and wants to keep it and I'm just curious if it's good approach. (I know the best way is to make usability test, but budget is kinda low and client himself doesn't have any analytics data).
The previous and next button could help preventing pogosticking.
Most guidelines against pogosticking are about making the result and category pages more accessible with more information while interacting.
Two great resources on this:
If the user is on a category page with products that are all potential products he or she wants to buy they would want to view the full product page of all products. The next and previous buttons could make this easier.
Keeping it not random would be wise. Just the next or previous in line as would be on the category page.
Too bad you don't have any analytics available. This would make it clear if the buttons are used by users.
I can't remember ever reading any data by NN Group or Baymard on this topic, nor can I easily find any other findings, so I can't enlighten you with any insights. So that leaves me with "no harm no foul". "If it doesn't hurt...". If you can think of no reason the buttons wouldn't fit into your design, I think you're left with doing what the client desires.
And do add analytics for your client this time! ;)
I think it depends on the products sold themselves a lot, as well as the User behaviour. Therefore, various strategies can be applied here.
Some products may be similar, and only have a difference in tiny details. Sometimes, products can be organised in a chain depending on the features (e.g. a NAS server with 256MB of RAM, 512MB of RAM, 1024MB of RAM etc.).
In those situations "next" means "better" or "of higher functional value", whereas "previous" means the opposite. In this situation, it does make sense.
Then, sometimes the offer may be really random, but as a user, you still need to dive into the details to decide. Like on Etsy, where searching for e.g. a wallet, you might want to go through either a list of thumbnails or navigate between them one-by-one. No "gradual" aspect of the offer applies here, you just look through a subset of your search criteria/category. Here, it also makes some sense, it's like Tinder for products then. But for that to work, I believe you need to focus on the technology part to support fast switching from one to another.
But, should the user be not interested in many of these products, they go through when going through the chain of previous/next, it is not a good idea to have it, as on every page they will just say "no, this is not something I am looking for". In those situations, it may be helpful to provide them with an excerpt from the list of the products available in the "next" and "previous" subsets, for example by displaying some thumbnail and the crucial features that would allow the user to decide. Then, they would be able to go to the e.g. 3rd next product, skipping the two that they could tell they would not be interested in at all just after seeing the thumbnail and the limited details.
No matter which approach you select, or come up with something even better, it's worth experimenting and collecting analytical data to make the proper decision. I know it is a limitation here, but anyway, listening to the users is the best way to design solutions that would work for them. If you are short on the budget, then maybe you could just do a corridor test with some of your friends, family etc.