The amount you squonk depends heavily on the squonk bottle, the BF pin (diameter of the hole and length), and the RDA/RDTA deck design which involves where the juice is dispersed and how deep the juice well is.
For example, no matter how full the bottle is in my Centaurus, there's always some amount of excess compression needed to get the juice to start feeding the deck. In contrast, there's very little compression needed to get juice up into the deck via the Pulse V2 - it's almost immediate. Same with the Dovpo Topside Dual. And as lackluster as the Aspire Feedlink Semi-mech squonk is, it also feeds very well into the deck.
The BF "Squonk" pin can vary in hole diameter as well as in length when used in RDAs vs. RDTAs - the length in an RDTA is probably twice to three times as long as a normal squonk pin.
Lastly, there are rebuildable decks that place the squonk pin dispersion hole at the bottom of the juice well, so that excess juice is sucked back into the bottle. However, many decks place the squonk dispersion hole(s) on top of the coils or split the juice to both sides of the deck to get juice to your cotton more quickly. If the holes are not placed at the bottom of the deck, then squonking will simply spit juice into the juice well and suck none of it back into the bottle. You need to watch out for decks that do this, as it's very easy to overflow shallow juice wells where you're going to end up with juice spilling out through your airflow holes. It might be best to find yourself an RDA that's dual coil and has the squonk pin placed directly in the center of your juice well. That way you can look directly down into the drip tip and see when your juice starts flowing, and how fast it's coming out. You can also see if your bottle is sucking back excess juice.
Dual coil deck with center positioned squonk hole:
Also be mindful of how much height there is between the bottom of the deck and the lowest section of the airflow:
Effectively, this Asgard Mini would need to be filled all the way to the airflow holes before it'd start leaking juice out while positioned straight up and down. If you have quite a bit of excess juice sitting in your juice well, that can leak through the airflow when you tilt it to your mouth. For this particular deck, the squonk pin will suck excess juice in the juice well, back into the squonk bottle.
A last note - I would stay away from RDA/RDTAs that use an unsealed flathead squonk pin. I've noticed this to be a common thing for Oumier's rebuildable atomizers. If the flathead ends of the squonk pin are not sealed, you're going to have a crazy amount of juice end up just sitting in the 510 compartment of your mod. Added pressure from squonking is going to want to force that juice somewhere it's not supposed to be.
This is how most squonk pins will come:
Squonk pins you want to avoid:
See how there's nothing to prevent juice from squirting out the sides of the flathead slot?
You will occasionally see flatheads with the sides sealed off. Excuse my crude Photoshop work, but I hope you're able to understand what I mean:
This keeps the juice where it's supposed to be - either in the deck or in the bottle.
