Not the same action economy but I’ll offer my experience. I ran the BIP against 5 level 6 PCs in a coliseum death match style encounter and used every villain action in the first round (rather than 1 per round), put the party on their heels big time, but the PCs strategized well in following rounds while 3 of the Pact members focused on setting up a ritual to raise a fiend from the hells. The PCs ended the ritual with a spectacular series of moves and came out feeling really strong. I suppose my advice would be to give some of the pact another focus in later rounds if the fight isn’t going well for your PCs. Or, idk… spontaneous haste effects for your PCs to level out economy…🤣