Adding and deleting bars

I worked through the pdf manual now and I hope that I will remember most things. As I am working on my first score that I am doing from scratch with Notion I am very impressed with the ease of the work flow. Most things are very obvious to find.
I am however getting to the odd things that I just do not find the answers for that easy. For example, I can not find the quick way to add or delete many measures / bars to my score. I know how to add bars one by one, i.e. use to "i" key shortcut and just click at the end of the score many times will add as many bars as I click, but is there no way that I can add, say another 50 bars easily?
In the same vain, if I write a score of only a few bars, I end up with many empty bars at the end. I know I can delete them one by one by first adding rests in all the remaining bars and then select them and then delete them all. Is there no easy command that I can just delete say 20 bars from the cursor onwards?
I am however getting to the odd things that I just do not find the answers for that easy. For example, I can not find the quick way to add or delete many measures / bars to my score. I know how to add bars one by one, i.e. use to "i" key shortcut and just click at the end of the score many times will add as many bars as I click, but is there no way that I can add, say another 50 bars easily?
In the same vain, if I write a score of only a few bars, I end up with many empty bars at the end. I know I can delete them one by one by first adding rests in all the remaining bars and then select them and then delete them all. Is there no easy command that I can just delete say 20 bars from the cursor onwards?