Ok, I see why you say JBF is wrong also. I've seen various ideas expressed as a "second benefit", but then, since this isn't something that's taught as such in the Bible, there will be many different ideas.
I do see it taught in the Bible. However, it is not as clear because the disciples walked and learned from Jesus, but didn't have the Spirit to not sin, i.e., Peter's denial. But after the resurrection, Jesus blew His Spirit into the 11 disciples, John 20. That was their "first." Yet, Jesus told them to wait in Jerusalem to receive POWER. That power is the ministry gifts, the "second." But to minister you must be a clear representative of Jesus and have already received the "first" the rebirth, the freedom from sin. That is how Peter preached to those 3000 devout Jews that this was what Joel said in Joel 2. That was one of the uses of "Prophecy" - supernatural understanding and interpretation of that Old Testament prophecy.
So at that time, here is how I see the two fillings.
The apostles - first filling - John 20
The apostles - second filling - Acts 2.
The 120 disciples - first filling - Acts 2 - Mark 16:16-18 - individual gifts for private use.
The 120 disciples - second filling - Acts 3:29-31 - 1 Corinthians 12 - corporate ministry gifts for the profit of all.
Perhaps the most common is the idea that the "baptism of the Holy Spirit" is something that comes later, and empowers us to actually live like Christians.
I don't see it that way. In fact, that's impossible. We MUST be born again and baptized with His power. Romans 8:9b "Now if anyone does not have the Spirit of Christ, he is not His."
About the gifts, is there always a 'waiting period'? Do you receive gifts only once during your life? I've long understood the gifts of the Spirit to be given by God whenever He chooses, whether immediately upon rebirth, or decades later, based on God's individual plan for each of us.
Not if you already believe they are real and for today. Many Cessationists (like yourself) can receive the power for freedom from sin, but do not have faith to receive the supernatural individual or ministry gifts. Though I went to church for 30 years believing in Jesus, but never having repented, I wasn't born again. But when I did repent, I got both fillings at once. Like both barrels. I was free from sin immediately, AND could see visions, hear is voice clearly - word of wisdom, word of knowledge, and prophecy - the personal revelations and the supernatural understanding of the Word of God. And learned immediately from His Spirit to receive 100% answers to prayer, where before, I never had an answer to prayer in all those 30 years. But I already believed in the gifts for about 6 years before actually receiving them when I was born again. Before that I was a Cessationist.
As I think about the idea of "second benefit", the way I normally hear it, like, an extra empowerment towards right living or special service, I can think of several times I've had what at the time seemed like that kind of advancement, but then, in retrospect, I've come to see how these just been the more visible parts of my growth, but that underneath were times just as important, just not as "stand out".
We receive the all-powerful Holy Spirit of Christ once. But He doesn't give us
all the power He possesses. So what you are experiencing are releases of His Spirit for growth. And that can happen many times - just like the 2nd filling is the start of the more powerful gifts. For you it may be the 10th if you ever develop the faith to believe in them. But in the meantime, you are growing.
As far as Jesus' primary reason for dying for us, I'd say it would be to provide the death in which we could die and live, so that we could be alive with Him. Both taking care of sin, and taking care of us.
Yes, Romans 6 and 1 John 3:5 show that.