Juliusz suggested I email out details to mobile-l on the following.

The question arose during an Opera discussion today whether hiding the Watchlist icon (which is the case on non-HTTPS supporting UX on Wikipedia Zero) on mobile web in the page menubar (not the same as the flyout "hamburger" menu) might make sense generally for <noscript> or lower JS devices? The Watchlist star on the page menubar takes up a lot of space, and as it's the only thing there at the moment (on en.m at least, icons like Edit and Add Photo aren't shown), hiding that menubar icon would free up some valuable screen real estate.

On <noscript> or lower JS devices (or browsers where RL suppresses JS due typically to challenges around timing of Deferreds and the like), using the Opera traffic as an example of such a browser, it seems like Watchlist usage is sort of low (this is at 1% sampling resolution). 

3

In other words, it seems users make it to the point of using the feature, but only about 300 times per day total. Meanwhile, the Watchlist start takes up valuable screen real estate for every pageview.

The usage of the feature is about 1/10 of the Opera usage involving submission of the login form (a prerequisite of watchlist usage).

$ zcat /a/squid/archive/mobile/mobile-sampled-100.tsv.log-20140409.gz | grep 'proxy=Opera' | grep -i 'Special:UserLogin' | grep 'POST' | wc -l

31

Which is about 1/10 of Opera usage of the login feature in any capacity (GETting the form or POSTing the form)

$ zcat /a/squid/archive/mobile/mobile-sampled-100.tsv.log-20140409.gz | grep 'proxy=Opera' | grep -i 'Special:UserLogin' | wc -l

331

Which is maybe 1/270 of an oversimplified "pageview" metric on Opera Mini, using text/html response types as a rough guide.

The relatively low usage of the Watchlist feature is probably symptomatic of the multiscreen flow on such devices.

-Adam