Do you prefer to show very few subcats on the home page or more? maybe all subcats for each main category?
search engines never gave any fixed criteria.. so you can do whatever you wish.. or keep changing. But yeh, google told to keep links on a page <100.
Mmm, I think that was an antiquated rule, based on their crawl resources that were limited more in the past than they are now. Might want to research that one before you accept it as gospel.
the only benefit I can see with more sub cats is that they should get spidered easier and more regularly being on the home page but you gotta keep a balance
Back in the days where directories could easily gain inner category page rank, people would chose a number that'd allow for some nice homepage PR juice to popular categories without spreading it too thinly. Now I'm not sure its worth it. I don't show any at all on the homepage of my fruitydirectory.
I've got a directory with over 300 categories from the home page that is #1 for it's main keyword in Google. Many of the next level pages have PR and are in the top 20 Google SERPs for their main keyword. However, the site has over a million pages and several thousand categories...so I need a lot of links from the home page to handle the structure. This is a niche directory and I doubt I'd be able to do the same thing with a general directory (mainly because the focus of the site wouldn't be tight enough to get any category pages ranked). So for a niche directory it works o.k. SERPs wise to have a lot of categories from the home page.