Splitting media items creates new lanes?

Hello, I am trying to learn how to work with lanes effciently. I have been trying to learn why splitting my media items creates new lanes. I can't figure out what I am doing wrong and hope someone here can offer some instruction. Thank you.

Thank you for the suggestion. This had occurred to me and I have tried turning those choices off and sometimes it works but more often the split clips keep opening up more lanes. I am also finding that sometimes exploding takes to lanes helps and other times it seems as if imploding lanes to takes helps. I can not figure out the correct combination of circumstances, and it is driving me a bit crazy. I am so glad to be learning about Reaper, but this particular issue has become a stumbling block for me. It seems like there must be some behind the scenes logic that I just have not recognized yet. Thank you.

I am stumped. I have tried every combination I can think of. I have watched Kenny Goia's videos numerous times, and still can't figure this out. What I want to do is shown in Kenny's video "Exploding and Imploding Takes" at 2:21 I can't figure out how to do the same thing he is doing. I want to split one of the takes but not all the rest, and I would like the split items to stay in their lane instead f creating a new one. Just like it is shown in the video. What am I missing? Thank you.

Thank you very much for the explanation and for alerting me to the possibility of enabling Track > "Free item positioning". I was unaware of Free item positioning and now that I have tried it I am amazed at the potential for its use. This feature allows me to work with a familiar workflow and offers opportunities I had not imagined previously. Thank you!