Take for example a (software development) project that has been estimated by the freelancer as N hours on a pay-per-hour contract.
From the perspective of the commissioner, how much buffer should be allocated to the estimate and What happens when this buffer is exceeded?
Similarly, how should the freelancer handle a situation where he/she expects to be far over the estimate. Should the freelancer take the hit and complete the excess for free, or should this be re-budgeted with the commissioner?
So to summarize: When the freelancer has exceeded the estimated effort, who funds the rest of the project, freelancer, commissioner, or both?
@jmort253 posted a strong answer to this very similar question. I'm looking for responses covering the perspective of both the provider and the client. What should the freelancer do to reduce costs on underestimations? What should the commissioner do to reduce costs on underestimations? How can this end with both parties happy (and each getting best value out of the other)?