The NFL already has had an unprecedented number of rescheduled games. The NFL hopes that won’t continue.

In a memo sent to all teams on Friday by NFL executive V.P. of football operations Troy Vincent, the league pointed out that it has “made more in-season scheduling modifications than in any previous season.”

“These adjustments have not caused significant disruption to the season,” Vincent writes. “As the season progresses, however, rescheduling options will become increasingly limited. Eventually, further adjustments will cause disruption and jeopardize our collective ability to complete the season within the current framework.”