I was reading RMAN book. FOr diffrential, it's all clear but I have question about incremental backup method:

If you have Sunday backup as level 0, this will backup the entire database. You do level 2 backup on Monday so whatever blocks changed from Sunday to Monday will be backup. you do another level 2 backup on tues so RMAN will backup blocks changed from Mon to Tues and from Sun to Mon as well.

Let's say, you do level 1 backup on Wed, the book said it will contain all the block changed from Monday, Tues and Wed. Thing I am not clear is that if level 2 will backup whatever the changed on Mon and Tues, why can't we do another level 2 backup on Wed instead of level 1??? Why do we need level 1 on Wed ????

thanks and have a great weekend.