Hey Auzzee--thanks for the info. The really important thing to remember is that if you tighten it down too much, the sealant will be squeezed out and it is possible you won't have a sufficiently thick layer of bedding material to keep the seal. The thicker the layer of bedding, the more movement it can handle w/o breaking away from the deck or whatever is being bedded to the deck.
The best materials will have a low modulus of elasticity so that the bedding can be compressed or will stretch to bridge the required movement/gap. Sailor's favorite "do everything googe" of 3M 5200 is not a low modulus material and while it's a great adhesive, it is doomed as a sealant for things that will have flexing/movement. Sika Flex is owned by (or owns) the Tremco company. As an aside, a lower cost way of getting the same performance/material is to purchase one of the Tremco silicon modified polyurethane sealants that is sold for the construction industry. There are dealers who carry both brand names and have a cross-reference to which-is-what
On tightening things down--we make a decision about how thick the bedding should be to achieve a successful long-lasting seal and tighten down the fasteners until we've achieved that thickness. Sometimes it's finger tight--sometimes it's just about all the way to where it needs to be. Then, we wait 24 hours and then we tighten up the fastener(s).
We tape off the item being bedded and we tape the deck around the item so that it is simpler to have a nice, neat job.