I have set up a routing with Lot Size of 1 and ALL operation times to be 15 minutes, zero queue time, zero set up time.
 
So for 8 operations, the lead time should simply be 8 times 0.25 hours which is 2 hours.
 
In running SH-N Generate Lead Times, for the above example with 8 operations, the lead time is 8 (days).  I also found that if I had 4 operations the lead time was 4, with 6 operations the lead time was 6.
 
From this I deduced that the system was allowing a MINIMUM of 1 day lead time for every operation.
 
I got the same results whether I was in DBA standard or DBA-ISTech.  I also found that SH-M Estimate Lead Times, was giving accurate results.
 
With my client, we have an average of 4 operations per component with short operation times, and can fill rush orders in less than one day.  So our solution right now is to manually enter lead times, but we would prefer to be able to use system generated lead times.
 
Does anyone have any comments or advice?

I thought I had tested this and couldn't duplicate it but I just created a new part number and gave it a 4 sequence routing each with 15 minutes and I confirm it uses 1 day per sequence.  Will send to programming.