Elite Dangerous: Value of Planet Surface Mapping

I recently started surface mapping planets to earn some credits. I found out that you can scan (and sell) surface maps even of planets that are not 'unexplored' but actually explored already... So this seemed a good idea and it pays out pretty well.

While selling mappings I have seen a vast range of value for selling seemingly identical data. I mostly focus on Earth-like Worlds and High-metal-Content Worlds, as those are (from what I heard) the most valuable scans. But even here:

I have sold surface mapping scans of Earth-like Worlds from anywhere between 250'000 to 1.5 Million credits. How comes? What makes one scan more valuable than an other? Is there a way to know in advance how valuable a certain scan will be?

Or does the data change value depending on where you sell it?

The data is the same price at all stations - the following table gives you the approximate scan values : https://elite-dangerous.fandom.com/wiki/Explorer#Scan_Values

Here FSS - Full System Scan DSS - Detailed Surface Scan FD - First Discovery Bouns - note that this bouns applies when you first Mapp a planet, even if it has been discovered already.

If you are on the PC, there is an application called Elite Dangerous Discovery (EDD) which runs in parallel with the game. Amongst other features it will give you an estmated value for every planet you come across - for example an ELW that you scan (even if already discovered) is worth 255k approximately.

These don't apply if the system is inhabited.