Always. I just click on the 'wrench' and add about 4% to the 'adjust total flavor %'

You can't just add x %'s or multiply flavorings and expect it to work. Some flavorings only work within a very specific range to produce a certain flavor profile with nuances, especially in a mix. E.g 1% may be good, but 1,2% may completely ruin the mix in the sense of turning it vegetal, floral, dry, harsh, chalky, spicy, earthy, overpowering and commonly muting other flavors.

Just because you heat less eliquid at once with MTL coils doesn't necessarily mean more flavorings will compensate for that. To a certain extend, more vapor means more flavor. There is a ceiling to that though as your olfactory receptors/brain can only sense so much. Most of the balance between heat/power, coil surface area and airflow amount is also relative to the dimensions of the atomizer you are using. You can't really get DTL flavor from a MTL vape, because MTL coils can only produce a limited amount of vapor before the vape becomes too uncomfortable. Bigger coils, with more surface area will require more power which will produce more heat for which you'd need more airflow. That will take your MTL vape into RDTL terrortory.

I'm not saying multiplying flavorings is impossible or that it doesn't work for anyone. Just look at the reformulated high nic salt eliquids. I keep hearing/seeing people say these companies use 40% flavorings. They could be, but that doesn't mean you should as an amateur mixer adapting other amateur mixers' recipes. Personally, I doubt if those claims are true at all. Your adjustments will depend on the specific flavorings you are using. The majority are simply not suitable for multiplying blindly. Technically, you'd have to redesign a recipe to adapt for MTL. Don't just go off total percentages, it holds no value at all. Most of the time, less=more in many different ways.

So, unless you are experienced and know the flavorings you are using very well, I'd advice to start with adjusting a mix down to 50/50 PG/VG. Not only will your liquids require slightly less time to steep, they will be less viscous, so more liquid can reach your coils quicker. You can also increase the surface area of your coils with "super fine" fused clapton wire. Compared to round wire, this needs a little bit more power to heat up and produces more vapor without becoming too uncomfortable to vape. If you are still using the OG Berserker from 2017(?), I'd look into upgrading that as well. The Berserker 1.5 mini, the Ehpro True RTA, the KF lite 2019, the Expromizer v4 and the SteamCrave Glaz Mini are all decent choices.

There are so many different people with different devices and preferences. In the end its about you and what works for you. Just try and mix up a few bottles, do some tests, see what happens ;)

On some recipes I found it necessary to increase the flavors by 15-25% most of the time 15% was enough.

If you are looking at ELR recipes, those honestly should be fine for MTL, rather than DTL

I add extra flavor for certain recipes, It can also be helpful if you have a device to try juices as you make them, then if you need to add a bit more flavor, or a bit more nic etc, you can dial it in while you have all your equipment out. I use an RDA on an older mod, and it has really made dialing in my flavors a lot easier. I wish you the best of luck, and I hope you have a wonderful holidays :)

i think steep time has to be respected sooo much more w the mtl effort. (as a tiny possible difference to get u there) the only reason i have and do stray from mtl style is because u just can't experience some flavors and overall profiles w/o intensely experimenting w flavors on a crazy patient mad scientist level. Mostly, though, u just need that heat and volume to get a read on anybody else's recipes. heat and volume! can only be compensated for or translated w an appreciation for precision tooling. I'd love to hear what folks have come up w on individual flavor tweeks(w this goal in mind)

Most recipes vary in their percentage and I would not say that there is a „fixed“ rule that you can apply. But here is what I do (same tank as you have ;)) :

If a recipe sounds really good, I will mix a flavor base, not the juice. You can change that in the elr-wrench. This way I can start at the recommended % from the original recipe and if I don’t like it, I can easily adjust the percentage by adding a little more flavoring.

If you don’t want to do that, I would aim for 10-15% flavor total with most recipes. Except the older ones, because back then there was mostly MTL :)