Are the ratio between egg types changed from time to time?

See the silph road article on egg rarity.

Basically, eggs are rolled from a list - there are 4 rarity tiers. The pokemon species is pulled from that list, and the egg is assigned the distance based on what's in it. The Gen2 update made 2k and 10k eggs significantly more common, as there are now two 10k species in the most common tier (drat and pinecone). Additionally several pokemon were moved down to a lower grade of egg, meaning more eggs would be 2k.

But - talking about ratios between distances is sort of missing the point. The species is rolled, and the distance of the egg follows from that.

It's not a coincidence! I am not a incubator user, unless during my trip to the other country or during some specifique event like double stardust. Even with one incubator, I can feel that I had a lot more 10k eggs about two weeks ago. I think I it's a service side change. I play in france by the way!

The only change I noticed recently (last 2 weeks) is the large number of pineco. But I consider just RNG, since initially I had only 1 pineco for about 3-4 weeks :) alongside 5-6 dratini.
In recent 3-4 days I've collected at least 2 10k per day. I usually run 3 to 5 incubators at a time.

I've posted about this before.
I believe that the mons, and therefor the eggs that drop, migrate with the same time pattern as nests. I.E., every couple of weeks.
If a nest is considered to be a place, area, etc., where mons spawn, but a certain mon species spawns more often, and that spawn rate can change on a timed basis, then why can't a pokestop be considered the same way?
It is basically a mini-nest-like-location where mons spawn in the form of eggs. Stops in a given area might be prone to deliver more 2K egg mons for a time period, then more 10K egg mons for a different time period. .
Most players have a tendency to always hit the same stops. I hit about 40 stops on my way to work, and then if I need to load up, hit them again on the way home. Sometimes there are others, but these 40 stops are pretty much every weekday. According to my backpacker medal, I've spun over 12,500 stops. I know from experience that certain stops are more prone to produce an egg than other stops. I even know that there are some that I have never collected a single egg from.
Lately, I hatch between 5 and 7 eggs a day. Multiple incubators, and I walk about 10 - 12 KM a day on average. With that amount of data, I can verify that I go through time periods where I only get 10K eggs at about a 3% rate, and other times where I get them at about 25% rate. I wrote about this just this past Friday, when I noticed an increase from 1 10K in 39 eggs, to 3 10K in 12 eggs. It seemed to change the same time as the nest migration on Wednesday evening.
Different studies have come up with percentages of both the value of the eggs, (2K, 5K, 10K) and the chances of the specific mons from the eggs, (common, uncommon, rare, ultra rare) but has anyone ever tried to determine if there is movement in the patterns based on physical location?
I'm not trying to imply that the specific MON migrates, but more that the mons in a specific group migrate, and this causes changes to the value of the eggs that are dropped.
Example: Take all of the mons in the group "2K egg" and assign them to be more prolific in New England for 2 weeks. At the same time, all of the mons in the group "10K egg" may be more prolific in the Pacific, West Coast area. Once the 2 weeks is up, a 'migration' occurs and the regional spawn rates change. . This may account for differences we see in the different studies.