We regularly examine customer bandwidth and disk space utilization data in a series of statistical analyses and use the results to define "normal". Although these tests vary from month to month, one thing remains constant: 99.95% of our customers fall into "normal" range. If your account's bandwidth or disk space utilization causes any concern, you will receive an email asking you to reduce usage. We strive to provide at least 48 hours notice to allow customers to make adjustments before we take any corrective action.

For example, you may certainly contact your host at any time, but when are they available to respond to your questions and concerns? How long will it take for someone to get back to you? Will there be someone to help you if your mission-critical website goes down at 3:00 in the morning? What language(s) do your host providers speak? Support in Malagasy is probably essential if you live and work in Madagascar, but fairly useless if you are in North America.
We use only the latest, fastest web servers available from Dell, HP and Supermicro. Every one of our servers has at least two processors, 16GB of RAM and four hard drives with RAID protection. We place a lighter load on our machines than the other guys do, so your site has breathing room during busy periods and you can run more complex scripts. And we use CloudLinux to optimize.
Many services offer so-called unlimited or unmetered service for whatever amount of bandwidth, disk storage and sites you use. It's important to understand that most terms of service actually do limit the definition of "unlimited" to what's considered reasonable use. The bottom line is simple: if you're building a pretty basic website, unlimited means you don't need to worry. But if you're trying to do something excessive (or illegal, immoral or fattening), the fine print in the terms of service will trigger, and you'll either be asked to spend more or go elsewhere.