Missions & Complexes

I've done exploration for a few years and I've the basic mechanics more or les down pat, there's just a little thing that still I dont know for sure and it nags me:
when I close a site, let's say a data site, in the same region respawn another after a little delay - the new one will be another data site or a random anomaly from the full region anomaly pool?
or, to put it another way, by not running all the crappy anomalies (data sites in null, combat with crappy npc like blood raiders etc.) I'm ruining my chances to get something better?
for eg I was roaming in Delve where you find dozens of crappy blood raiders anomalies (nobody run those) and ZERO other sites, not even wh.

This is a bit more complex than just a list of systems in which a site respawns. I dont know exactly how it works. But what i know for sure is, that if a site is cleared another one will pop up.

Of course there are more factors which have in impact on the respawn, like population and how may do exploration, timezone you play in, security level and many more.

In the region im home we have the problem that many explorers not inhabitated there just pass through and do the sites in the way of "best cherry picking". By simply checking what is inside the can with a cargo scan. Then they leave the trash cans and empty cans simply unopened and fly on. So we have sometimes like 20 sigs in the systems, and all are just with 1 or 2 empty or worthless cans and they dont despawn until someone opens them or until the natural lifetime of the sig has passed by, which is also random like e.g. the WH timers. From 8 - 48 hours.

As this is a persistetnt problem we dont do the highsec sites anymore and leave them. Why?

*) most of our regions experienced explorers are wortking in lowsec and null anway and highsec we dont bother.
*) bypassing explorers waste their time to only find worthless sites and complain in forums.
*) in lowsec and null bypassers will be shot immediately and if "cherry picking" then we chase them until they leave.
*) Those shot down wont come back too soon and we have a good supply stock on sister scanners and probes.

So sum up - highsec mostly few worthless sites not despawning cause of cherry pickers and low/null heavy guarded and defended by inhabitating explorers, and of course no cherry picking.

Times are rough and i dont bother shooting if i see an explorer in my home systems i dont know and who is obviously not from the nearby systems as we talk to each other and have contact marked most of them. Competing onthe market and remain successful is more or less a war.

How to avoid this effect of not despawning sigs easily?
Fly to the empty can - activate analyzer - close window - activate analyzer - close window - empty can explodes. (12 secs)
Signatures then despawn and respawn accordingly. Not clearing them out is just cutting in the purses of those idiots doing this "cherry picking" and when they dont make ISK in highsec and are shot like all the time in low and null the situation will clear itself anyway somewhen.