Frequency is supposed to indicate how often the page contents change.
Some pages like contact info, change seldom.
Some pages like pages that output weather data, change almost every time you look at them.
Technically the latlong-convert page is dynamic so it changes every time it is used. They goal was to get it listed as a site link, but that has never happened. I’ve flipped it around a couple times with no results.
The mystery is how and what gets those generated. I’ve had some sites where I can do it on a regular basis like tnetweather site. There are a ton of sites which have a link to tnetweather on them (like more than 800). I’ve had other sites where nothing every seems to work even though they have as good or better sitemaps.
They key appears to be when a site is relevant, ie seen as a relevant site to others. Kinda of hard to fake that. either you have a lot of quality sites linking to your site as a relevant site or not.
One example is a site I created for a Fishing guide in California Clear Lake area. No relevant sites link to his mainly because most of the bait shops that have websites no longer control or know how to update them (kinda funny actually) and others won’t or will only after they have known him for a couple years. Tough business to crack into. so his site which is indexed, has a decent sitemap etc… has no real ranking on Google and traffic to it is slow.
I ended up creating him a brochure which an 8-1/2" piece of paper cut into 1/3rd strips with printing on both sites. It is a flyer of sorts which he has gone around town and put in all the tourist info bins at all the hotels, motels, bait shops etc… that seems to have started to work and is starting to get people to look directly at his site for more info.
Having a good sitemap helps, but without the links to go with it, nothing happens, and it is hard to get into search keyword maps until you are either relevant or pay for things like adwords.