Keep in mind, though, that a % increase in tax and a % chance to succeed out of a 100 behave differently.

Increasing income bonus from 50% to 55%, and then from 55% to 60% is just a linear increase, giving the same benefit for each step (at an income of a 100, the stages would be 150, 155 and 160, each star providing exactly 5 additional income). Increasing chance to succeed in assassinations from 90% to 95% and then from 95% to 98% is a vastly different thing, as the first cuts our risk of failure from 10% to 5% - or halves it - and the second one from 5% to 2% - which cuts it to 2/5 the risk of before. The last 3 percentage points are worth more than the previous 5.

Not to derail the thread, though, I'd like to also mention the greatness of the latest patch's increase in town-stationed agent's xp/turn from 1 to 3. This is actually pretty significant in the early stages of the game as a Metsuke hired in turns 5 or so now hit rank 2 after just 7 turns as opposed to 20. As rank 2 can give them 2 additional town management skill on top of their innate extra from ranking and since administration cost is very low when you're low in provinces, this makes early Metsuke significantly more efficient to get and that in itself makes r4+ Metsuke easier to get in the later stages of the game. Still not a Silk node - but I'll take it.