There is a middle ground between Big 4 and one person consulting. I used to work in the services/consulting org of a decent sized software company that sold data products. We had ~25 consultants in the US and were focused on deployment and light/medium customization. Our selling point was that all consultants were like surgeons and did focused work. We were not a staff augmentation group.
Two great things came from this 1). We didn't have enough people to support multi-year enterprise projects and all the BS that comes with that. If a customer had a big project we'd bring in a partner (e.g. Accenture). 2). Individual consultants could push back on unreasonable asks. For example, more than once I got asked to configure something (e.g. databases, firewalls, etc) that the company I worked for did not sell. I could simply say that I could provide info (e.g. schema recommendations, what ports to open), but the customer had to find somebody else to do it. If you work for a big consulting company the services manager will come in, say we can do it, and things just grow more complex from there as more and more people get dragged into things. Or worse, the services manager leans on you to do something totally out of your expertise because they don't care.
At least 75% of the projects I worked on were reasonably scoped and budgeted. Of course 3 years after I started somebody somewhere decided the consulting team needed to generate more revenue and take on bigger projects.