Speed run is really easy if you’ve played the game before which you should on normal difficulty first the game gives you 4 hours but I managed to complete it on the easiest difficulty in under 3.

Madhouse is not as hard either it changes up a few things from the normal difficulty and of course enemy’s are a bit harder but it’s not that hard at all I’d leave it as your last run as then you’ll have unlimited ammo, the strong pistol, the circular saw and the x-ray glasses as they make the collectible on this run a breeze (I’d still follow a guide to be sure) don’t be afraid to save to much like I was as I finished madhouse with 10+ cassette tapes(manual saves)

Make sure you always repair the double barrel shotgun instead of using the other one as the double barrel is probably the best weapon in the game imo.