The following failure modes should always be taken into account when run a project!!

1. people making mistakes:
People make mistakes is no surprise to us, however, iterative and incremental development were invented. Incremental development lets the team learn about its own development process as well as about the system being designed. During the process, the team members examine their working conventions to find out what should be improved, including team structure, the techniques, or the deliverables.It also allows people discovered the inevitable mistakes and repaired in a tidy manner.

2.people prefer to fail conservatively rather than risk succeeding differrently:
People intended to use the normal conservative strategy, a 'guaranteed' stdandard ourcome, rather than one that might work but might blow up in strange ways.

3.people prefer to inventing rather than researching:
In our earliest school days, we are instructed not to copy other people's work, not to help each other, and to be as original as possible in all but rote memory acts.However, we should be a good  'component assemblers' and accept a less glamorous design happily if it can be put into use quickly! we are in the serious competition!!

4. Being inconsistent creatures of habit:
We are creatures of habit who resist learning new behaviors, and at the same time we tend toward inconsistency!

5. Countering with discipline and tolerance:
"PSP is extremely rigorous, and if no one is asking for my data, it's easier to do it the old way" one trainee of PSP said! yeach, the alternative to requiring discipline is being tolerant of individual variation. The good methodology calls for the team members to form consensus on the minimum compliance needed in the work products and pratices. Each suggests the use of standards but does not require that standards be enforced!! Keep in mind: strict adherence to ineffective practices leads to an ineffective team.