As far as I know spamming BR is the only way to get and keep IB stacks in the Frenzy build. Personally I’m not sure it’s worth it, but I believe Rage maths it out in the guide, [Guide] H90 Frenzy: A simple guide
The main post links to a later post with season 22 discussion, here: [Guide] H90 Frenzy: A simple guide - #421 by Rage-13139
And this one is the math specific to IB. [Guide] H90 Frenzy: A simple guide - #130 by Rage-13139
There’s a few other posts in the thread with people’s experience with it, so it may be worth it to skim though the whole thread.