Character transfer process

So I got BL1, Handsome Jack Collection. I know for BL2 and Pre-Sequel I can transfer my characters. I was reading the process of it and says I can only do one character at a time. Is there a faster process or is it one at a time until all 10 are done?

PS3>PS4 transfer

One at a time but it doesn’t take that long.

I started to kinda debate on the transfer. I hadn’t played either in about 3 years. Forgot how to play them since 3 years. So in a sense of rather start fresh and not help my friend when my guys are strong already