if you mean overall estimate earnings then yes they do because they average it out based on All time views so it can go up or down , for example say 1 month you get 1 mil views and your estimate says £400 but the second month you only get 500k views.. your estimate will go down by like £250 ( roughly random estimate) its not saying you'll deffinately earn that much less and it can go up the next month if your views increase / more videos equalling more views,
If your views go down your estimation will go down as your biggest viewing month is thought of as your most estimated money earnt month.
Sorry if i've completely misunderstood your question but i tried XD and sorry if i'm difficult too understand.