Main futures generally refer to futures contracts with the largest trading volume and positions. Generally, the month with the largest position is the main month. When the recent month is also close in real time (that is, close to delivery), its position will be transferred to the distant month. Before it is transferred to a certain extent, it is still the main contract, and it will not become the main contract until the position and trading volume of the far-month contract exceed that of the recent month.

It's not necessarily an overload.