You are IMO half-right, KJM (and I've brought this up in the past v. the devs / CS):

1. Misconception:

Negative percentage values, such as training or movement speeds are not calculated as ...

[New Speed] = [Old Speed] x (1 - [Reduction in %])

... but rather as ...

[New Speed] = [Old Speed] x (1 / (1 + [Reduction in %])).

It's a bit like extracting the sales tax from a product priced at X €.

2. Plarium error

Having said that, one quickly notices that when applying the above formula, the duration to complete Athens level 30 should be 156h:48m, but the game shows it at 169h. I did a bit of the underlying math, and it seems that the Phylarch reports the remaining duration assuming there are no other bonuses or enhancers at work, though most of us have at least a few scrolls invested in Academy "signing speed".

I'm aware that this handing of negative percenages calculations seems rather counterintuitive, but it does make sense when one thinks about it. An example:

• You earn 100$ / day.
  
• Your boss informs you that from now on you will be earning 50% more.
• Great! I'm now making 150$/day.
• One month later ...
• "Business is bad" says the boss, we're reducing your pay by 50%
• Rats, well, I guess I'm back to 100$ /day.
• Your next paycheck reads: 75$ / day (50% of 150$). WTF?

Hello The Irate Penguin. Thank you for the new algo. I updated my spreadsheet. 

I think the same situation happens to the Phylarch construction bonus. I see the same time difference even if I have 25% maximum bonus. I am doing the port upgrade now, same situation.

It is a mystery......

kjm said:

It is a mystery......

... wrapped in a conundrum :-)

This has been brought up in one or two previous threads and I recall the player did create a CS ticket at the time, though I don't know what became of it. I'll try and write up an example of how this is currently working (or not working) and send to CS or ask one of our CMs. Stay tuned ... but don't hold your breath :-).

Cheers
P.

Hello, I have issue with the Skill discovery speed bonus - it doesn't apply any bonus after activation. Please see below the screenshots, before and after activation of the bonus.

dadogggothigh said:

Hello, I have issue with the Skill discovery speed bonus - it doesn't apply any bonus after activation. Please see below the screenshots, before and after activation of the bonus.

Hello, Archon!