Aggregated Schema Reviews for Services, Ok? Site wide or per service?

[Len Telapost]

I am trying to figure out precisely what Google does or does not allow for structured data markup for aggregated reviews.

I have seen a few local businesses using schema markup for aggregate ratings.

Let's say they have 50 Google reviews. If they're using microdata they'll add a (marked up) sentence to the bottom of their service pages that says something like "We're rated 5 our of 5 stars based on our Google reviews." Then in search results the pages get a 5 star rich snippet. They properly link out to their Google reviews and accurately report their rating. One site I monitored has has snippets displaying for years.

My question is- are they doing it correctly or are they eligible for a penalty? As far as I can tell they aren't breaking any rules.

Also, most people implement the markup on one page- it appears that using review markup sitewide would be a mistake. Or is it?

Google's pages are a bit confusing on this topic, especially when local business pages are offering services but are highly reviewed.

The only thing Google has to saw about this:
https://developers.google.com/structured-data/rich-snippets/reviews?hl=en&rd=1#aggregate_ratings

Additionally, a business such as an auto repair company may have multiple offerings such as "oil changes" or "transmission repair".

Recap:
- Are aggregated Google reviews safe for strutured data?
- Is implementing them site wide a bad idea?

If anyone has any experience with this, feedback would be greatly appreciated.

 

[Len Telapost]

As a follow up to this, for the time being, I am going with this page https://developers.google.com/structured-data/policies which doesn't explicitly state that reviews may NOT be aggregated for services, but it does state which structured data MAY be used, such as data to describe the business, its location, contact information, and opening hours...

 

[Tony Wang]

I definitely see local businesses getting sitewide snippets, and have done it myself, but David Deering advises against this. He wrote this post recently: Understanding Google's Updated Structured Data Guidelines - Local University

The last few paragraphs discuss your question; my understanding is that aggregate reviews are ok for snippets, but not sitewide. I think David recommends a unique/specific review snippet for each individual service page. For example, "oil change" reviews on your Oil Change Service page.