A business with a broad multitude of independent clients is more predictable and lower risk than a business with a small handful of major clients. If your client base is too broad and diffused, it will lower the value of your business. You'll have enough clients for stability and diversification, but not so many clients that you require additional people to service them. If you're not growing you're declining. In the current marketplace there is no such thing as business stability.
Buyers look for a documented stream of revenue over a period of time.
It gives them confidence that they will experience the same growth in the future. If your business is growing extremely quickly, you may be able to ask a premium for your firm. Different buyers value different things. To maximize the value of your business, know whom you want to sell it to. Then you can build your business to have most value for your ideal buyer.