I never felt the need to purchase any Time Saver items (things you buy with real-world money to gain XP and gold relatively quicker). I found the level pacing between the main mission to the next gave you a steady and fair progression. And I managed to skip most of the mundane missions.
Still it's hard not to feel a little bit cheated that there is an option to do things quicker.
What Ubisoft could had done instead?
Skins, damn it. Sell skins.
Ubisoft has enough fan base that people will buy skins and other cosmetic items that would allow players to personalized their assassin for online experience.
"Assassin's Creed Odyssey" gives emphasis in combat, naval battle, and epic armies clashing. Now translate that into online multiplayer. Ubisoft is no stranger to multiplayer, previous AC games allowed player-assassins to roam around cities, hunting each other and "Watch Dogs" let players hack each other. However, it doesn't seem like those attempts yielded any fruitful results, which is a shame for Odyssey as it is combat-oriented.
It sounds like a solid formula for online play, doesn't it? Or would it kill Ubisoft's "For Honor"?
Online play would also make an excellent feature to go along with the bounty mechanic, where you can be hunted by other players or you could go hunting them.
Also, skins would allow better Photos - since apparently people love doing that in-game.
Ubisoft can continue to offer the Time Savers - since I imagine with an emphasis on online experience, people would want to level up as soon as possible. (Oh, and people would say the online experience is a "pay-to-win" system, sorry Ubisoft, there's no escaping it.)
I support Ubisoft's plan to keep single-player alive through these adventure games, but it's hard not to imagine a game like "Assassin's Creed Odyssey" to not thrive in its online play potential.