Maturity Model should we got to Level 5 (top)

Few organizations can afford to achieve and stay at the top level. Most of them are happy with a middle of the road level - 3.

Level - 3 a more stable environment, more effective in terms of cost/benefits

Depends on the capabilities and the business dynamic your operating in. Might "drive for 5" on some and "settle" for 2 on others. I don't hesitate to move the pendulum over time either. Examples, this year and last Portfolio Planning & Prioritization dictated advanced (~4) in my space and Innovation we let hover at 2+. Make the best choices/investments you can make and roll but...striving for 5 across the top is never sound in my view (not attainable, affordable or necessary). 2-cents

Because my background and doctorate degree I work a lot with maturity levels into each field whre maturity level has been used (started with CMM suit). First, you have to undestand what maturity model you are talking about: Software? Project Management? What other?. Second, you have to understand that get a maturity level could be seen from two point of views: because the organization needs to implement the maturity framework because a need to compete with others in a business field OR because your organization really believe this is the way to improve itself. But people could walk along a maturity framework to improve themselve by using the Personal Software Process.

Thanks Sergio,
There is an overall rating if we can call it like that and level for various business process that would compose it.
Should CMM be use for all ?
I will look up for Personnal Sowfware Process, first time I ear of that.