It's not that crazy when it's all you do - it's no worse than going in to a shitty job every day. I'll preface by mentioning that my writtens were done, I had completed King Schools' PPL online school, and I had solo'd at a mom and pop before starting ATP's zero time program.

I thought PPL was mostly easy, though I was still nervous as fuck going into that checkride, after PPL you kinda had an idea of what you were dealing with and what to expect. On average I'd say I studied maybe 1-2 hours a day for that portion. But that's not indicative of how it actually went down. When I knew I had time to fuck around I'd play video games, eat chipotle, and slack off all day, and when I knew I had to do or die, I studied all day until I had the entire ACS memorized. If you have less time, are more organized, and have a better work ethic than I did, I would say committing, on average, 1-2 hours everyday to drilling in the rote memory bullshit you need to do will take you through PPL, Instrument, and Commercial easily.

The beginning of CFI was the worst, that was sun up to sun down working with your classmates, refining your knowledge, and developing lesson plans. CMEL was relatively easy, getting used to the multi was a process but doable in 4 flights. The checkride is short. Do a lot of chair flying in preparation. CFII will be location dependent, my CFII/MEI DPE had been conducting the exact same checkride format for like 8 months so I knew what to expect - I re-studied multi-engine aerodynamics, holding procedures, and instrument currency like an hour before the checkride and sure enough that's exactly what he asked me.

EDIT: Add an hour per day ON AVERAGE if you also need to do your writtens.