How many and what do you usually look for?
Topic on Talk:Wikistats 2.0 Design Project/RequestforFeedback/Round1/Detail page two wiki compare
I can compare pageviews or activity in several wikis. I look for relative trends (e.g. is one wiki growing faster than another?). For example, I can compare pageviews of Cebuano Wikipedia (continues massive bot growth) and Waray-Waray Wikipedia (stopped bot growth) to see if it has any impact.
I happened to compare all 290 Wikipedias, but using tables.
Yes. Usually 2 or three, and I look for trends, so these views are relevant on the long term. But if it's all the same, why not include multi-wikis view everywhere?
Yes. This comparison is important specially when addressing content with a focus on specific themes, like gender gap.