At some onsite visits I have seen NetWare Administrators use CRON jobs to run unattended DSREPAIR's. This is not good! I love this quote, "you don't check your oil level by draining it all out, you use the dipstick."
If you are going to do a repair, you shouldn't use the Unattended option unless you have a really good reason, and those essentially don't exist anymore. If you need to fix something try to fix that one thing instead of throwing your entire database through the DSRepair blender. Usually, things will be okay if you run the repair but some rare situations could cause pain and suffering you will not want to deal with. Don't hammer nails with shotguns ... find problems and troubleshoot them specifically if at all possible. Learn to use iMonitor effectively.
DSRepair is not a maintainence tool, it's a fix tool. Using it properly requires that you understand the problem first - don't use it for a shotgun approach to troubleshooting, as you will nearly always get yourself in deeper by doing that.
Check out these two very good articles on DSREPAIR