If you expect to have people still starting while the initial participants are finishing, having separate systems for collecting start and finish reads is ideal. However, if you are attempting this sort of race where you're using a single chip system to collect both start and finish reads, there is an important new setting on the Results 1 tab specifically for this scenario. Make sure you specify that you're using Common S/F for start reads. On the Timing Location properties, use the new "Allow Mixed" setting. With this setting, you can have a true mixture of start and finish reads - start reads for one participant after a finish read for other participants. Be sure to set an adequate gap factor.
IMPORTANT: When you import chip reads, use a zero gun time. This way, both start and finish reads are stored as "Time Of Day". When you import chip reads, participants that have more than one pair of reads that satisfy the gap factor you've set, RD will automatically use the first one. But, you are given a grid showing everyone with more than one pair of qualifying reads so that you can select the pair you want.
When you run the Overall and Age Group results reports, use this setting. The result is a well documented report - showing the time of day each participant started the race and the time they finished. Obviously, the scoring is by net time.
As we finally get to the point where restrictions on races lessen, letting people onto a race course in small increments may be your only choice for a while. Reporting like you see below will be useful in documenting how you are deriving finish times.
Thanks Roger.