I've learned a few things while ripping my collection. I'm pretty sure I could have gone faster with 3 drives... *maybe* 4. Like they other guys said, 5 to 7 minutes is typical for a clean CD rip. What I really learned though was to slow down and not try to bang through as fast as possible.
The big deal is to validate your metadata. Take a look at the back cover of the CD. Look at the song names and make sure they haven't been mangled in some way. For multi-artist CDs do they have the Artists and Song names reversed? This happens. The release year seems to be wrong on maybe 10% of the CDs I ripped. Maybe less... maybe 5%. But it's definitely a problem.
Even album titles are "wrong" from time to time. Mostly because someone put extra information in the title. Like putting the release and CD catalog number in the Album title. Multi disc albums require some scrutiny too. I find that people tend to change the Album title for each disc, including "disk 1", "disc 2", etc in the title. It doesn't belong there.
Album release info might be worth capturing. Is that copy of Dark Side Of The Moon that you just ripped from the Columbia label? Or is it the Harvest version? No? Maybe it's the Mobile Fidelity version then. There are something like 14 different versions of Dark Side Of The Moon. That's just one example of many. You'll never know what you have unless you capture the information at rip time. I suggest a custom field to hold this information. Possibly including the catalog number or discogs number if this kind of thing is important to you.
Fixing all of this stuff before you rip, or just after you rip, in the tagging program of your choice, will save you time later. Assuming you want high quality precise metadata. If you don't care that The Smashing Pumpkins Melancholy And The Infinite Sadness gets divided into two albums instead of showing up as one (it's a two disc album), then this might not be a big deal for you. But with 3500 CDs to do... I'd think you'd want the metadata to be as correct and precise as possible.
Brian.