Too much waiting while rejoining

The first time I register my device and join it to TTN, it takes a maximum of 3 minutes. However, when I reset my device, the subsequent attempts for joining take much longer, about 10 minutes, 15 minutes, or even 25 minutes.

Additionally, each join request is published 10 minutes after the other. How can I can faster this process? Is this delay a fundamental part of the protocol?

I’m testing different ideas in my code, and I program my microcontroller many times. It’s not logical to wait this much time!

Duplicate posts don’t help as it spreads the answers around - please be patient & wait for a volunteer with time & expertise to answer.