> #!/bin/sh
> cd /home/bbbs
> ./bbbs bom create 2:250/1 +crash > /dev/null 2>&1
> touch work/rescan2.bsy

Why only one poll here? You can do more:

#!/bin/sh
cd /home/bbbs
./bbbs bom create 2:250/1 +crash > /dev/null 2>&1 ./bbbs bom create 12:456/7
+crash > /dev/null 2>&1 ./bbbs bom create 123:4/5 +crash > /dev/null 2>&1 touch
work/rescan2.bsy

> */20 * * * * /home/bbbs/poll-fido.sh
...
> */40 * * * * /home/bbbs/poll-fido4.sh

You run first cronjob three times per hour, last one only once a hour. Is that
really what you want?

--- BBBS/Li6 v4.10 Toy-3