Should I use a tanning bed I got a little sunburned in but for less time?

The first day I went to a tanning salon I used it for 5 minutes in a standing one and I saw no results. The second time I was in the standing one for 8 minutes and had a slight tan line (barely anything) The third day I tried a laying down one for 8 minutes and got slightly burned on the back of my legs but it was barely noticeable and I got a little tan. The 4th day I tried a different tanning bed for 9 minutes and got sunburnt on my chest pretty badly, but everywhere else was tan. I skipped a day since I got sunburnt, but I want to go back today so should I try the last one I did since I actually got results but for maybe 6 minutes? Or should I just use a stand up one since I already got burnt a little? Thanks! PS- no cancer bullshit please.