Nah, it's doable with some planning far ahead, but it's not really worth it... All the rewards are mostly trash, except double drops.
I haven't spent a cent starting from March. Since I kinda returned into the game from September, I reach 4th or 5h tiers, with a very rare occasion to reach only 3rd.
Here's my plan:
- Never spend stamina without double drops activated or without a contest going on. You may spend Stamina for 3xElite and 7xNormal for quests if you need Team XP to level up.
- Always buy 4xStamina daily, that's 480 stamina for 200 diamonds. Don't forget to acquire quest Stamina, that's 180 more.
- On diamonds weekend continue the daily buy, on the last day of the contest spend more Diamonds to get to the wanted tier, if the 4th tier is not very far and it has a helpful reward (like Crystal Shrine). If you're not far from 5th tier you may consider burning some Stamina or even burning your Double Drops item, but that's very rare.
- With two weeks of collecting Stamina you should have at least 8k Stamina prepared for orange contests. On last day of it check how far you are ahead to the 5th tier. If it's not far off, you may consider burning stamina without activating double drops, and get another free double drops. But usually you'll activate your double drops, go wild with your accumulated stam, get lots of gear and reach 5th tier to return your double drops without a hassle.