People develop software. This simple, inescapable fact invalidates most of the available methodological advice. Often, software development doesn't meet human needs, acknowledge human frailty, and leverage human strength. Acting like software isn't written by people exacts a high cost on participants, their humanity ground away by an inhumane process that doesn't acknowledge their needs. This isn't good for business either, with the costs and disruption of high turnover and missed opportunities for creative action.
What do people need to be good developers?
I chose practices for XP because they meet both business and personal needs. There are other human needs; such as rest, exercise, and socialization; that don't need to be met in the work environment. Time away from the team gives each individual more energy and perspective to bring back to the team. Limiting work hours allows time for these other human needs and enhances each person's contribution while he is with the team.
Part of the challenge of team software development is balancing the needs of the individual with the needs of the team. The team's needs may meet your own long-term individual goals, so are worth some amount of sacrifice. Always sacrificing your own needs for the team's doesn't work. If I need privacy, I am responsible for finding a way to get my need met in a way that doesn't hurt the team. The magic of great teams is that after the team members develop trust they find that they are free to be more themselves as a result of their work together.
While intimacy feels great, work is still work. Private details of life confuse team communication. I talked to one team in which a member, once he got comfortable on the team, talked about private details of his life every morning. No one else was comfortable hearing about his private life but they didn't know how to confront him. Eventually, the senior team member took him aside and asked him to keep private matters private.
I try to separate my life into private matters that I only discuss with my spouse, personal matters that I discuss with those who have earned my trust, and public matters that I don't mind talking about with anyone. Figuring out which is which is not a simple matter, nor is it simple to figure out who to trust. The rewards of this separation when it works well are effective communication on the job and relationships that are valuable in all aspects of my life.