If you want to connect up to 4 devices, then it is enough. There is no general rule. As long as you do not plan on any RAID setup or want to have 4 distinct SSDs (mechanical HDDs and optical drives do not benefit from 6Gb/s much), you are probably fine with 4.
If you want to connect up to 4 devices, then it is enough. There is no general rule. As long as you do not plan on any RAID setup or want to have 4 distinct SSDs (mechanical HDDs and optical drives do not benefit from 6Gb/s much), you are probably fine with 4.
4 is more than fine. Most users either go for single HDD or SSD+HDD, and even if you upgrade storage with more HDD, you still have ports to plug them in. 4 is fine for any general user, I'd not require more than 3 unless I run a server.