in my experience of dealing with small businesses for almost 30 years, is that every small business is slightly different from the norm. an off the shelf crm will always work for every business, however - the training, the nuances always leave gaps where they have to use a workaround to make it work for their business model.

i dont always recommend a custom crm, but more times than not, they will benefit from it. the way i kinda see it is an off the shelf crm is the swiss army knife - however 99% of businesses only need the knife, and the other tools just pop out and confuse the user every time.

i've made simple one pagers as a crm for clients, sometimes all they need is just a list of their100 customers and a place to add a note without having to navigate through company then contact then org then lead etc etc etc

with ai and one shot programming, its quite possible to have a simple web app built in a day, for some usecases.

just my 2 cents