What is your program on the other days?
Do you have other goals than improving the getup (that would explain the program on the other days)?
I started swings and getup S&S style on two days a week about one year ago, to complement a 3-days per week barbell program. I kept it light (16-24kg getup, 24kg swings). Just needed some conditioning (swings) and to learn to really keep my shoulders packed (I find getup very good for this for me). It worked, because they were just the 20% assistance lifts of my training, not the 80% where I focused at the time (barbell big lifts), and I did not mind not increasing the load.
Then I found myself in your situation: in October, I had to travel every week for work, and could not do getup whenever I wanted.
I transitioned to NW in the week, and did a swing+getup training session once a week on weekends for roughly two months: goblets squats 3x5x24kg, swings 10x24kg 1H, Getup 10x24kg (some sets sometimes with 16kg).
I bought a 32 kg in this period and could introduce it in swings. Progress was good in swings, not because I magically improved, but because the 24kg swings were already very light at that moment for me.
On the other hand, I was unable to increase the load in the getup. I could perform only one set at 32 here and there, no more. It taught me a few things about alignment I did not notice at 24kg, so I improved my getup technique at 24, but not the load.
Only when I could focus on S&S 5 to 6 days a week (end of December) was I able to progress on the getup and use the 32 for all sets.
Basically, my conclusion would be not to expect to find effective programming for the getup with only one session a week. Of course, it is just my personal experience. Your mileage and strength may vary.