As a sales consulting business ourselves we are pretty well qualified to comment upon the ability of management consultants to plan their service offerings...

Frankly, we've never worked for a consulting business who has a really well worked model to gradually turn consulting into a services-based relationship with a client that "never" ends.

The problem is with the upfront sale.

We work hard to develop propositions for our clients where there is an "annuity" that pokes out of the back of engagements, sustaining the relationship until the next bulk project starts. 

Unfortunately it seems that much of the time our clients gets hired to "fix a problem" and then loses sight of the reason why we worked to get into that account... and cannot turn themselves back into the business that we pitched them as initially.

Our friend Ian Brodie spends a lot of his time helping professional services companies with their propositions... and actually although harder to break in - all of those companies have business models which are annuity-based.

If consultants generally are ever to build businesses that have real commercial value (and can sell for that value) - then they will need to work how they don't leave the relationship to stagnate whilst they deliver - and also how they generate repeat business. 

Otherwise feast & famine will remain how they run their businesses.