When I slowly dial up the beats per minute (BPM), the value does not increase / decrease with equal steps, and in some case it is not possible to get a value with the decimal = 0 (like 85.0 BPM).
The delay is in reality set in milliseconds. When it is shown in BPM, you see a conversion of the ms value, with only the first decimal displayed.
The formula for conversion is 60000 / time (in ms).
500 ms = 60000 / 500 = 120,0 BPM
501 ms = 60000/501 = 119,7 BPM
502 ms = 60000 / 502 = 119,5 BPM
2290 ms = 26.2 BPM
If you display in BPM and you want to increase the delay time (thereby decreasing the BPM value) the steps will show 120.0, 119.7, 119.5, 119.2, 119.0 etc
For the same reason, some values with decimal = 0 (i.e. 85.0 BPM) cannot be obtained.