to get as close as possible…
First of all, you need to measure how many SP you burn per e.g. minute before anyone can actually tell you a number.
Secondly, make sure to deactivate every attribute you don’t need that consumes additional SP (e.g. the Dragon Fall defence ignore attribute).
To come back on topic:
SP recovery is covered by both the SP recovery stat and SPR[since it increases SP recovery].
To nullify the need for SP potions, you need an amount of SP recovery that is equal or larger than your SP consumption via skills every 20 seconds (without Squires Refreshment Table Yoghurt) or every 10 seconds (with Squires Refreshment Table Yoghurt effect or when sitting down).
There are also other things you can do to improve the SP recovery (e.g. stand inside the AoE of Dievdirbys’ Statue of Zeymyna [SP recovery tick time -5 seconds] or sit down every 10 seconds to receive the SP recovery for sitting and refresh the tick timer), which would directly improve the recovery over time, thus lessen the burden on equipment/SPR requirement.
Since every point in SPR adds about 2,6 SP Recovery, you can calculate from there how much raw SPR you need to cover your base SP consumption. You can always replace SPR partially with item awakening on high level equipment (you can get 80-100+ SP recovery on unique & legendary gear from 330/350 onwards).
If that’s not enough, there is also the option for 1-3x 10 star Mushcaria card for additional 60 SP Recovery per card.
Since I don’t know your needs, attributes, skill levels, etc I can only estimate, but judging from my own SP recovery of my Exorcist, without Yoghurt you’d need at least 2000 - 3000 SP recovery to cover your SP recovery completely without potions[did a quick calculation and the dragoon skills alone require at least 1500 SP per tick including the SP discount from the helm].
At level 390 you have a base SP regeneration of 240 as Swordsman, so you need the equivalent of about 677 SPR to go without potions and without Yoghurt completely.
You can enchant all your armor with SP recovery (I’m averaging 80 SP recovery per armor, so - 7*80 = -560 SP recovery required), which would reduce the requirements to 1200 SP recovery or 461 SPR.
Given you can get free SP recovery from collections(+43 possible, but at least two of the collections are way too hard to complete so let’s say 30) and some SPR from quests(+3) and collecting titles (19 titles required for +4 SPR), that’s another ~50 SP recovery, so you still need about 442 SPR worth of SP recovery.
There are lots of ways to get it via equipment (e.g. Masinios Shield, random stat gears with 30+ SPR), but you’ll need at least 200-300 base investment in SPR nonetheless, even with all these investments.
That’s why suggest giving up on living without potions either way, since your recovery rate with lvl 15 alchemist potions and a few points into SPR will be enough to cover your every need.
If you have about 300 SPR in total, a single SP potion will recover 4590 SP every 30 seconds.
Since you need about 2000+ SP every 20 seconds, this should be more than enough to cover your SP needs, given that you also will recover 1020 SP+ every 20 seconds passively.
