I would like to add my 2 cents:

Whenever I can, I recommend against more than drive letters C and D and advice to use mount points for everything. It’s hard to make sure all servers have the same disk layout (in fact rarely ever) – especially when it comes to test and dev environment. I will spare you a list of advantages here.

Second: for most SANs and environments in general it nowadays does not harm to put tempdb on the same drive as the other databases. In fact it’s mostly better (more disks). And only if tempdb becomes a bottleneck, then I would move it to a dedicated LUN/Raid-Group.

Of course, as usual, this is also a matter of personal preference and (bad) experience.