When you are on a project with a stipulated SLA (service level agreements), like 1000 concurrent requests per minute, it is always good to be selfish.
That is, to hog all the system resources to yourself and avoid shared hosting.
What happened recently was that we had a client who asked us to develop an application and host it for them, with a certain SLA on response time. However, the client would also like the server to host another project.
We did not think much on it. However, at regular intervals, our application would slow down, with long response time. We wondered if we had to tune our application, web server, or databases.
Turned out however, that the other project hosted by the client would, at regular intervals, eat up almost 100% CPU usage for a short while!
That would surely hurt our stress test.
So we informed the client, shut down the other project, before doing our stress test.
Lessons learnt? Always be selfish and go for dedicated hosting. You might not meet a reasonable client every time.