Multi-timeline rate limited

[dontpnc]

I've been testing something with the multi-user timeline using 30 accounts separated into endpoints like this:

localhost:8080/user1,user2,user3,...,user15/rss
localhost:8080/user1,user2,user3,...,user15/rss

I've performed approximate calculations, considering 217 guest accounts and the Twitter API's limit of Api.search: 50. I'm sending requests every 3 seconds to two endpoints, resulting in 2 requests every 3 seconds. The calculated rate is 600 requests every 15 minutes. According to my calculations, I should need at least 12 guest accounts to avoid rate limiting. However, despite having 217 accounts, I'm experiencing rate limiting on more than 18 accounts (screenshot below).

I'd appreciate your thoughts on this issue. The rate limiting occurs consistently, I've also experimented with lists, but Twitter seems to delay 10-20 seconds for tweets to display in lists.

Any insights or alternative approaches would be highly valuable. If you've faced a similar challenge or have suggestions, I'd love to hear your experiences.