Never tried exactly what you are asking but with wordpress website i usually apply simple rules that are best from user as well as from SEO perspective...
- Never Confuse!
Let’s not get your visitor confused when visiting your website or else you will witness a good amount of bounce rate increase on your website. If you think adding a category will make the side bar more confusing then try to avoid it because this will impact your SEO as well as user reaction on the website is one of the important SEO factor.
2. Over Optimization
I have witness quite a few examples of over optimization and honestly speaking over optimization is simply addition of similar content and keywords again and again on the page that does not make any sense but if adding a word around 4 to 5 times and its making sense with the content then i think it won’t be counter as over optimization of keywords on the page...
3. Always think about Visitors
Think for visitors and search engine will follow you! This sounds ironic but true as visitors are the end point and as search engine is changing on frequent basis it is more bent towards how users (visitors) think and react to different designs, websites, niches and how much time it spend on each page.
I think not with this particular problem but with very on-page problem you should focus more on users (visitors) instead of search engine bots only.