And if it has notepad nearby it isthe best tool .
Make a route (preferably circle) of 10-15 systems. And scan all signatures in each system at least up to 25% to see what this signature is.
Each signature has own unique ID. Write it down along with "Group" of signature. If it is not radar, skip it, unless you want to scan "Unknown" further to 75% and find out is it combat plex or WH.
It will takes may be an hour, or two or may be three, but when you get to the starting post, you will have complete list of all signatures in systems along your route.
To figure out if there is new sig ( spawned in system ) drop 1 or 2 probes with 32 AU covering whole system and scan. If there is new signatures in system, "ignore all other" and scan only new ones.
The second round of scanning your rout will be ten times faster and effective.
Once you get use to this, you can increase number of systems in your route. If there no, or only few new sigs respawned, take a break, grab some coffee, watch TV for a while or serf Internet, reread this blog or fly to Jita and give away your hard made ISKs to scammers :-)
And scan all over again.
If this method doesn't work, it is a time to think about another area of your ops.