A cyclical methodology has no governors to control oscillations from one cycle to another cycle. Without governors, each cycle generates more work for the next cycle leading to time schedule slips, missing features, or poor quality. More often than not, the length or number of cycles may grow. There are no constraints on the requirement team to ``get things right the first time.'' This leads to sloppy thinking from the requirement team, which gives the implementation team many tasks that eventually get thrown out.
The architecture team is never given a complete picture of the product and hence may not complete a global architecture which scales to full size. There are no firm deadlines. Cycles continue with no clear termination condition. The implementation team may be chasing a continuously changing architecture and changing product requirements.