We can somehow justify that with Lalo growing impatient and acting in a rushed way, which no doubt will be his undoing. He wants to get it done ASAP and so he just can't wait anymore. Probably he would have waited Howard out, but when he heard him say that he would work relentlessly to bring Jimmy and Kimmy down, he thought he would have been a problem to eliminate.
Anyway.... congratulations to the author trolling on Twitter, the one I quoted. Yeah, maybe he's since in saying that they didn't plan a mid season break, but I'm sure he told that to not have people anticipating a major shocking cliffhanger and maybe try to guess which one.
Poor Howard. Poor, poor Howard. I never felt sympathy for his character as much as now. His tearing down of Kim and Jimmy was absolutely on point. Yeah, it's a TV show, Jimmy is the protagonist, we rooted against Howard and eventually we sympathized with him when it turned out that Chuck was the real asshole, but seriously, he said it so eloquently - what did he do to deserve all of that? he's an asshole, he got daddy's help, he sided with Chuck, so out of petty revenge they ruin his life and carrer? who made Jimmy and Kim judge and jury of what should happen to regular, decent people who happen to have some flaws? and he was even depressed on top of having marital problems.
So many parallels with both Chuck and Hank.... with Chuck, the meltdown orchestrated by Jimmy and the lucid realization of what Jimmy's plan was - Howard got it down to the last detail exactly as Chuck did with the Mesa Verde paper, and with Hank, the whole "moderate antagonist that you have to realize is actually better than the protagonist and eventually dies tragically".
That scene shocked me, I kinda plan my viewing evenings to not run too late beyond my usual bedtime (hey, the day after is a working day), I had to scrap those plans and chill out a bit because I was too shocked (eventually I went for other shorter stuff, I needed those 10-15 minutes to calm down, this wasn't just another "eh, episode over, time to watch another show" thing). I was worried just as Kim and Jimmy and I didn't even properly saw the killing 'cause I was too busy saying "no, no no... NOOOO HOWARD!!!".
Nothing will ever beath Hank's death in this universe, but this probably comes in as a close second.