Trying to figure some $#!T out

So I'm trying to figure out the rhyme/reason/formula for how much time you save when you 'help' your friends with they're upgrades. For now I'll just post the samples until I figurez it out.

Sep 29

Pebble Shiner lvl 4-5

1h49m (109m) left

Saved 5 mins

4.56%

Twig Snapper lvl 3-4

45m30s left

Saved 2 mins

4.42%

Storage Silo lvl 2-3

40 mins left

Saved 1 min

2.5%

Tesla Tower lvl 3-4

1d 14h 5m (1440+840+5 = 2285 mins)

Saved 1h 54mins (114 mins)

4.99%

Twig Snapper lvl 4-5

1h40m (100m) left

Saved 4 mins

4%

Sep 28

Storage Silo lvl 3-4

19m (1140s) left

saved 57s

%5