Project Euler Forum

I'd like to ask how a new problem proposal is determined to publish after acceptance?
Will the administrators try to "estimate" its difficulty and separate those "difficult" problems so that they will not be published consecutively?
Since there is a summer break in ProjectEuler, is it true that a "very difficult" problem will appear as the last problem just before the summer break? (For example, "Cake Icing Puzzle" and "Coloured Graphs" are two very difficult problems dominating the summers.)

When we develop problems a tentative difficulty assessment is done (Hard,medium,easy).
When we need a new batch of problems one of the admins makes a proposal from the ready problems according to the HMEMEM sequence, (hard,medium,easy, medium,easy , medium).