I used to have multiple web hosting accounts but figured out that I can save well if I sign up for multiple domain name hosting account and move all my domains there.
Simple math - I have 3 domains paying $9 per month for each web site - my monthly hosting expenses are $27. I found a multi domain name hosting provider that charges me $20 monthly so I save $7 per month. I can save much more if I register new domain names and launch the web sites. The only drawback is that usually you can have one main user that manages all multiple domain web sites. You cannot share it with others or you break the service agreement.
The only drawback is that if the server goes down, all your sites that are hosted on one multi domain hosting account will be down….