First the prevailing stories:
1. Blacking/Striping a tape gives continuous timecode and is essential for any shoot.
2. Mixing different brand tapes with different lubricants is bad for your video head.
3. Reusing tape is a bad idea and you should buy new tape everytime.
Timecode
DV tapes rerecords timecode once you rerecord over the existing material. So essentially it's new timecode anyhow. You may also run into problems mixing timecodes. You also double the workload by having to stripe each tape, not to mention the wear on the camera (which is really negligible). Why people advocate doing it is because back in the Beta days, you needed to get consistent timecode.
Why do you need to do it? Because when you review whatever you've shot, the tendency is to overshoot the clip on tape into timecodeless tape. And these people either don't use the END SEARCH function if available OR they didn't roll on for about 5-10 secs after, which gives you the buffer for previewing.
Another possible reason is Sony's own low power standby mode, whereby it stops spinning the drums and powers down the entire tape transport. Now I've never had this problem personally even with QUICK REC on. My timecode has always been pretty good.
Here are a few good habits to avoid timecode disruption:
- Roll about 3 seconds before and 5 seconds after shooting. So even if you try to review, it will have a buffer to protect from creeping into blank tape.
- Use the END SEARCH function on your camera if you have one after review. It'll save you lots of grief in capture.
- QUICK RECORD function: I've never had a problem but some have had it. So if you are not shooting subjects that need faster recording response... turn it off.
Mixing Different Brands of Tapes
Over 10 years later and still it pops up, much like striping/blacking. 
When Sony first came up with their DV tape, they used a wet lubricant whereas other manufacturers like Panasonic and TDK went with dry powder lubricant. They obviously didn't mix well together and caused much havoc. This was in 1996. In 1997, Sony and other manufacturers made sure their respective lubricants didn't mess each other up, essentially ending the problem.
Think about it. If the problem existed anymore, then Sony couldn't sell tapes to anyone who's used a drylube tape on their camera or vice versa, risking lawsuits. Do you think they'd live with that for 10 years?
Still it's cheaper to buy tape in bulk so if you have a preference for a brand for whatever reason, stay with it. But don't worry too much if you have to buy another brand in a fix. Just clean the tape head first with a tape cleaner of the same brand.
Reusing Tapes
If you black/stripe a tape, you're reusing a tape. For some who believe in this practice, they also say it's good as it tensions the tape to the camera and removes production flakes which usually occur in the first minute or so of a tape.
Sony has stated their tapes started showing irrecoverable dropouts and defects after 150 recordings. Adam Wilt has used a tape for record and playback for at least 300-500 cycles. Before TIVO, I used my mini-DV deck to record TV shows and have used those tapes hundreds of times with no problems. For most people, if the tape contains some good stuff that needs archiving, backing up to an old tape isn't a bad idea.
Manufacturers of tape want people to keep buying new tape, just like any other manufacturer. For the greener folks, there's plastic and energy waste to consider. For the professionals, $9 for a tape is cheap insurance. Still not every new tape is going to be error free. For underwater use, you're not going to shoot gems every time. So a backup copy on an older tape saves on tape storage space (I have over 400 tapes from shooting video since 95). I started reusing tapes (no more than 5 times) since 2005. I've bought 10 tapes since then.
So good habits to form with shooting is:
- Clean your tape head with a cleaner tape after 50 hours of shooting.
- Use ethynol alcohol to clean the tape head after 25 hours of use or before each trip. Oh and use a clean Q-tip
- Record colorbars for the first minute of the tape to remove manufacturing particles.
- Rewind the tape and remove from the camera before storing the camera away.
Please note these are just recommendations and only for discussion purposes. 
