Thanks, good to know! I spent some time doing H&D curves and things but this was all without a pre-soak so suppose I should do those again ideally.
As for my process, I use Xtol replenished at 20C in a rotary process with a development time of 10 minutes for CHS ii sheets. I use a JOBO 2500 tank and 4x5 reel but built my own rotary to spin the tank using some 3D printed parts and an Arduino (ATTINY85 specifically) to spin a simple DC motor. I spin the tank in one direction for 10 seconds, then change directions. It spins at around 45 RPM or so. So the film is being constantly agitated except at the very beginning when I'm pouring in chemicals. It's here that I think I may have caused some of the streaks.
Here's an example:
To me it looks like the developer splashed around and makes me think it was me doing that during the fill process. In the 2500 I only use 400-500ml of chemicals typically since it's constantly spinning.
The above process gives me a gamma of 0.71 but a CI of 0.62. For 35mm I've been using a dev time of 11 minutes using the same process where I get a gamma of 0.62 and a CI of 0.61. I've only just started doing H&D curves and these measurements were made from graph paper so not sure how accurate they are, though the negatives look good in both cases and 10 minutes was my "by-eye" before I did all the film tests (though for many of those I WAS using a pre-wash).
My thoughts to remedy this are to use the pre-wash as mentioned. This seems like the easiest thing to do but I wanted to be sure it was a recommended solution. Ilford, for example, doesn't recommend a pre-wash. I noticed with a pre-wash their films seem to have what look like scratch marks on the non-emulsion side and I have yet to figure out why. I don't have that problem with any other sheet films (Adox included). It's why I stopped the practice as I was trying to be consistent across all films, though when I was pre-washing my CHS ii, I never had any streaking using the same process as the above.
My other thought is to pour in the chemicals while it's spinning. I can do this with a small tube and a funnel, but will only be able to use up to around 400ml of chemicals as I need to keep the top off the tank to do so and will also have to pour in the chemicals more slowly. I was getting some streaking with C-41 recently as well and it makes me think it's also during the pouring process so thinking this is something to try for all developers.