I think the whole raise your price advice thing isn't an across the board thing.
If something takes you forever to do and it's low margins, that's the type of work you raise your prices on... Or better yet outsource.
It's like banners. There's a dozen shops that sell them for $2 a sqft.... I used to get a banner a day, 4x8.... $64 for a banner. To load the machine, cut, hem and grommet... It's just not worth it. But hey, $64 was $64 when I was just starting out, so I never turned it away.
Now I'm at $6 a sqft because I hate banners and it's not worth it to me. I still get the odd banner, but not like before... So it's freed up my time for more proffitable jobs... I still do banners for my regulars, I charge them less, but still way more than what the banner garage printers charge.
Raising costs to lower work is more so having the freedom to pick and do what you want, a focus on an area you specialize in, imo at least.