Let me tell you about the front and rear seals. Some folks have had bad experiences using them, and some of them would perhaps tell you to throw them away and just use some high temp RTV bead along the front and rear channels.
I can't fault them, once you have a bad experience, it is hard to act any other way, but I have done it both ways, and I have not had problems.
I have been a bit eager in the past while installing an intake or two using the RTV bead along the channels, and I have set the intake down and then thought in checking that the valley is clear of debris, and I have lifted the intake back-up again. :nono
Once it is set-down, it should not be lifted again. Otherwise, the RTV could spill-over the side toward the lifter valley, so the only way to get out of this mess is to lift it back out and clean it all up, and then try again. But with the rail seals, this would not happen. If the rail seals are used (and I prefer using the cork material ones Vs, the rubber/plastic ones), a small bead of RTV still is needed at the end of the rail seals to plug that area between the head, the rail, and the intake.
At any rate, you don't want bits of RTV left in the valley. With the engine heat, it will cure, and then it will float and flow where ever the oil goes. It is known to have plugged oil channels in the crankshaft and blocked precious lubricating oil to bearings.