In the days of Windows Server 2003 there were no native tools to expand a partition into contiguous free space; however, you could “extend” it to another drive but this wasn’t the same. Thus, back in ‘the day’ you had to provision enough storage to grow with the server and updates. If you were intelligent enough you would have created a separate partition for data but in my experiences this was never the case and stuffed to the max C: partitions were common. However, with the proper tools you could have extended the NTFS partition if you were comfortable enough doing so (and had a good backup). Today the majority of Enterprises are running Windows Server 2008 and this includes a native feature to extend a file system into free space you provided on the drive, similar to extending the file system on a Linux system.
Thus, I highly recommend only giving your system enough space as needed if storage is at a premium for you and extend as needed, especially if you have third parties demanding ridiculous storage requirements you’ll never use.