My current conclusion, which in my case is currently producing promising results.
Copy the contents of the Insta 360 X3 SD card to a terabyte SSD drive. Structure the Insta raw data into groups of up to 2.5 hours of recording time. To do this, I create the following subdirectories: 1, 5, 10, 15, 20, and 25, into which I move the Insta raw data. This means that directory 1 will contain Insta raw data 1, 2, 3, and 4, and directory 5 will contain Insta raw data 5, 6, 7, 8, and 9.
I then load only one group at a time into the InstaStudio software. This ensures that the Insta software runs stably and efficiently. If I export video files, such a group fits easily into a terabyte SSD drive (600 gigabytes of storage space required for a 2.5-hour drive). When rendering the Insta videos, I create segments with a maximum length of 5.50 minutes each. Longer videos generate numbers of more than 2000 GPX points in Mapillary. Mapillary has difficulty processing such videos, and they then get stuck in yellow in the timeline Processing times - #25 by eserte.
So I only created segments with a maximum drive time of 6 minutes. As a reward, I can output high-quality mov files instead of mp4 for better image quality.
I then reduce the Insta 360 GPX track by a factor of 10. In a subsequent check of the GPX track using the (OpenStreetMap) JOSM editor, I check for outliers. I cut out faulty sections, for example, due to a tunnel, and redraw the gaps by hand.
A final VBA script fills in the manually added data. nodes again with an interpolated time. My script uses the last usable original GPX time and the beginning of the GPX continuation.