With version 13.0.0, the limits on unit improvement levels in the Workshop were removed and two new categories were added:
one for merchant ships and one for freighters.
Although it is a nice addition to be able to increase the cargo space of these two units, there is a small side effect: sometimes upgrading merchant ships can actually be a disadvantage.
The upgrade affects cargo capacity. Instead of 500 per ship, each upgrade level adds +20 capacity. The problem is that the loading time during looting cannot be changed. For example, with no upgrades it would take 33 minutes and 20 seconds to load the looted goods, but with a level 10 upgrade it would take 40% more time.
A good improvement would be to add one more category, called “Merchant Loading Speed”, where each level could increase loading speed by 0.6. This way, players could balance cargo capacity with faster loading when pillaging.
And if you want to protect weaker players from suffering more raids per hour, you could add a limit so that the level of the Loading Speed upgrade must always be less than or equal to the level of the Merchant Ship Cargo Capacity upgrade.
This way, the total pillaging time would remain the same.