I will take a stab at it. I think it depends on the health of the industry and the economy.

If things are going great, tons of money is being made, pilot pay scale is low, then it is certainly in the best interest of the company to drag feet and maintain the "status quo" for as long as possible.

Conversely, if things are going bad, economy is not great, and pilots are being paid above and beyond the "industry average" because all the carriers are signing whipsaw agreements, it is likely that the pilots would have to sign a concessionary agreement. In that case, it would be in the union's interest to drag things out as long as possible and maintain the higher pay scales as long as possible.