The ICL method can be confusing and difficult to obtain good results especially if you are going back and forth with the crank instead of in one direction only.
As many engines as I've done over the years I just check the intake open point of the #1 intake lobe and leave it alone if it's at or close to where it needs to be.
I do NOT use double roller or multiple keyway timing sets, only factory link belt type and source out the 3/4" wide sets for my engine builds. This makes moving the cam around a little more difficult, but well worth the effort, IMHO.
EVERYONE out there since WAY back in the 1970's when I got into this hobby runs right out and buys a "double roller" timing set like it's some sort of upgrade. Most are just OK some are a little better and some are just plain JUNK. The ones that fall into the decent category will have billet sprockets, seamless full roller chains and multiple keyways to move the cam around. I still woln't use them here in my own engines.
One of my mentors ran a very successful Stock Eliminator Camaro and told me decades ago that the factory timing sets and much stronger than the roller variety, and they have constant tooth contact, absorb some harmonics, and will last the life of the engine.
So jump ahead to 2000 when I built my first 455. The company I sourced all the parts from highly recommended that I purchase a 9 keyway Rollmaster timing set, so I went off course from what I typically do and bought one. It did fine for a few years but I was driving the car almost every day and racing it as often as I could get it to the track.
I was racing in Northern Ohio one evening and the car started to slow down, WAY down, but oil pressure was fine, fuel pressure was fine, no internal noises, etc. I put the car on the trailer and pulled the engine over the weekend. Figured I freshen it up and restore power. Turns out the ONLY thing wrong with it was that the very expensive double roller seamless timing chain had failed. It was so loose you could just about walk it right off the gears!
I replaced it with a Melling 3/4" wide set and the engine was fine till I replaced it in 2009. The new engine has a Melling timing set in it and just happened to have the water pump/timing cover off recently to repair a coolant leak and the timing set looked perfect........FWIW......Cliff