Mashing doesn't normally take 4-5 hours. It does take extra time, but only an extra couple hours. If an extract batch takes 2-3 hours start to finish, an all grain batch takes 4-5 hours start to finish.
Basically, instead of heating roughly 2-3 gallons of water and steeping some specialty malts roughly 150-160 for 20-30 minutes, you're selecting a specific water to grain ratio (1.3-1.7 quarts per pound is where I usually am depending on beer), and heating it to a very specific temperature so that it mixes with the grain to leave the mash at a very specific temperature (usually in the 147-158 range depending on the beer). Brewing software is enormously helpful to get the right temperature for your strike water to hit your correct mash temperature. And then instead of 30 minutes, you're going for 60-90 minutes. And then after that you rinse the grain bed (sparging).
Like mentioned above, going BIAB there's really not much difference between that and steeping grains, just a bigger grain bag and paying more attention to temperature. And then if you have a second kettle you can heat a few gallons of water to 170-175, remove the grain bag after the mash, dunk it in your second kettle and stir a bit to sparge it, combine the two kettles, and you're good to go.
That's the process. If you already do full boils, you should already know the amount of wort you need pre-boil to hit your batch volume, so it's just a matter of making sure that you the mash and sparge volumes right to hit that volume. Which you'll be able to dial in over a few batches.
It's really not all that difficult. More variables and more room for error, sure, but it's not as hard as people make it seem like.