When do you use grip lead or plain?

Lads, 99% of the time I use a grip lead, can yous share some info on when and why you use plain lead? Targeting flat fish? Or Rays even? Or allowing your rig to roll in the surf?

Any info appreciated.
Thanks

You have pretty much answered your own question
Grip leads at distance if there is a strong currant, would not use them in close, but saying that I'm sure people will have other opinions

So a plain lead in close for bass?

Its not as simple as long range grip lead close in plain lead.
It will depend on what species you are trying to target and how strong the tide is, sometimes a plain lead will lead to missed bites if the lead is not heavy enough to set the hook.
Sometimes a good compromise can be a pyramid lead it will provide slow movement and enough resistance to hook a fish.

I also use long wire grips on very rocky ground to hold the lead out of crevices and cracks in the rocks. works a treat... in certain locations.

Casting a plain lead at a 60degree angle on a clean beach can allow the baits to roll and cover more ground, this technique can be good for flatties in the surf.
I also have some grip leads that use soft wire rather than hear wire for use on rough ground. Using a grip means the lead doesn't fall into a crack and jam, and the soft wires bend on the retrieve rather than snagging. - That's the theory pity it doesn't always work