I did a test comparing the scan speed of DMR One Frequency systems vs DMR comventional channels. I chose 128 frequencies, put them in 8 groups of 16, and gave each group a color name. I created a Favorite List with a conventional system and a DMR One Frequency system. In the conventional system, each color is a Department with that color's 16 frequencies. In the DMR One Frequency system, each color is a Site with the same 16 frequencies. So it's an apples-to-apples scan speed test.
I videoed the scan of these two systems, so the relative scan speed can be compared. Scanning the DMR One Frequency system takes about 7 seconds.
OTOH, scanning the exact same 128 frequencies as a conventional system takes less than 2 seconds.
Link to video:
https://1drv.ms/v/s!ApJIS-l4xqPtgrogadYvbZh-mUSjhQ
Conclusion:
There is a bug in DMR One Frequency System scanning; scanning non-trunked DMR frequencies should be just as fast, regardless of whether they are configured as a Conventional or One Frequency System.
Note: The sequence of color groups in both systems is Red, Blue, Green, Yellow, Orange, Purple, Black, White. When the conventional channels are being scanned, sometimes the Department is scanned too quickly for the color name to show in the video. For the conventional channels, Modulation was set to NFM and Audio Options were set to NAC/Color Code Search. Decode was set to Auto/8 for both conventional and One Frequency. The One Frequency system had ID Search turned On.