(B' U' F' R) // EO (4/4)
(D2 F2 B2 D' F2 U' F) // DR, 4b2 2e (7/11)
D' B2 L2 [R2 U'] // HTR (5/16)
R2 L2 // 2E+slice (2/18)

[] = U2 R2 U2 R2 U // 2E2E (+3/21)

Optimal from eo, first eo I tried and I had this 21 from 15 min. Sort of threw the rest of the attempt and seems like there is no easily findable sub 21. Tried inserting the 2e in the DR sequence but there was no 20 sadly. 

Still 19.67, quite a long time since I had this mean (more than 1 year)

F' L B' // EO (3/3)
(L B2 L F2 L' D) // DR, 4b2 4e (6/9)
(F2 L B2 U2 R') // HTR (5/14)
(D2 B2 L2) // Leave slice (3/17)

Slice in +1

I stopped at 40 min hoping to not see a 17 in the solutions

Obviously there is a sort of findable 16.

D' R' U F' B // EO (5/5)
R // DR-44 (1/6)
U2 L2 U' L' // DR, 4a1 2e (4/10)
(U R2 U L2 F2 L2 U') // HTR (7/17)
(B2 U2) // Leave slice (2/19)

Slice in +2 but

D' R' U F' B // EO (5/5)
R // DR-44 (1/6)
[U2 L2 U'] L // DR, 4a1 2e (4/10)
(U R2 U L2 F2 L2 U) // HTR (7/17)

[] = U D F2 D F2 D2 // (+3/20)

NICEEE

(U' D2 B' R2 D') // EO (5/5)
D2 B2 R2 F' R F' // DR, 4b2 4e (6/11)
(U2 L) U2 F2 L // HTR (5/16)
B2 D2 F2 L2 F2 // finish (5/21)

R U L2 D' // EO (4/4)
(B' L2 U2 R2 B R') // DR, 4b2 4e (6/10)
B D2 B' U2 F' D2 L2 F // HTR (8/18)
(L2 F2 L2) // finish (3/21)

There was a sort of findable 19 from this start:

R U L2 D' // EO (4/4)
(B' L2 U2 R2 B R') // DR, 4b2 4e (6/10)

DR-flip into EO

R (B' L2 U2 R2 B R) // EO (7/7)
(D2 B R2 U2 F) // DR, 4b2 (5/12)
(L2 U L2 D) // HTR (4/16)
(L2 U2 F2) // finish (3/19)

U L D' F // EO (4/4)
[D' // DR-44 (1/5)
B2 R] F2 B2 U // DR, 2c3 (5/10)
D2 L (R U2 L) // HTR (5/15)
(B2 R2) // S (2/17)

There is a easy +4 from the B2 inside HTR but I just had fun inserting another +4 inside DR:

[] = D B2 R2 B2 D2 B2 R' // (+4/21)

Optimal from EO

L' B' R2 F' // EO (4/4)
R' // DR-44 (1/5)
D2 B2 U F2 R2 D2 R // 4b2 2e (7/12)

then

L' B' R2 F' // EO (4/4)
R' // DR-44 (1/5)
D2 B2 U // JZP (3/8)
(D' R2 D) // DR, 4a1 4e (3/11)

then

L' B' R2 F' // EO (4/4)
R' // DR-44 (1/5)
D2 B2 U // JZP (3/8)
([U' B2 U]) // DR, 4a1 (3/11)
L2 U2 R2 B2 R // HTR (5/16)
B2 [D2] // 2e2e (2/18)

[] = U' F2 D2 B2 U' // solved (+1/19)

Crazy

(D L2 B' F' D) // EO (5/5)
(L' U2 F2 L B) // DR, (5/10)
D2 L' (R U2 R) // HTR (5/15)
(D2 F2 U2 L2 U2 B2 R2) // finish (7/22)

Simplify for 21

And then I found the 9+3 and another 21.

B' D' F' {L' // EO (4/4)
B} // DR-32 (1/5)
(D2 U F2 U2 B' U B') // DR, 2c3 2e (7/12)
([D B2 U' L2 U]) // HTR (5/17)
({F2 B2 L2}) // E+S (3/20)

[] = (U R2 U' B2 D) // E (+0/20)

{} = L F' B D2 F' B2 R2 // S (+2/22)

U R' (F R) // EO (4/4)
(U F) // DR-44 (2/6)
(D R2 D' F) // DR, 4b2 2e (4/10)
([U2 L2 B2 U' L2 D']) // HTR (6/16)
(F2 B2 L2) // M+E (3/19)

[] = (D2 R2 F2 D U2 B2 U' *) // E (+1/20)

* = (U2 R' L F2 R L') // (6-1/25)

U {R' L2 F2 B2 L R' F2 R L' U'} B2 ... 

{} = L F2 L R' D2 F2 B2 U // -2/23

BUT

U L [F2 L R' D2 F2 B2 U B2 U2 D']

[] = (D' F2 U' B2 D2 R L' B2 D2) // -1/22

Man that was complicated... 9+4 has a easy 21. And then there is the 18.

(L D2 B' D) // EO (4/4)
D2 F2 L' F2 U2 B // DR, 4a1 4e (6/10)
D2 L' // HTR (2/12)
(B2 L2 B2 U2 R2 F2 U2 F2) // finish (8/20)

(B' L' F) // EO (3/3)
(U) // DR-44 (1/4)
(B2 R D2 L B2 D') // DR, 4b2 2e (6/10)
U2 B2 D2 L D2 L2 D2 L' // HTR (8/18)
U2 D2 L2 // Leave slice (3/21)

Slice in +1

(B2 L' U) // EO (3/3)
(R2 B R2 F B2 U2 R) // DR, 4b2 3e ext (7/10)
R2 B L2 F // HTR (4/14)
L2 U2 L2 D2 R2 F2 L2 // Leave slice (7/21)

Slice in +1

Getting dizzy with this kind of DRs and HTR in 13... bad solving

D' B2 L B // EO (4/4)
D R' // DR-32 (2/6)
U2 R' U R // DR, 4b2 4e (4/10)
D' F2 U (R2 F2 U' L2 U) // HTR (8/18)
(L2 U2 R2 F2 B2 D2) // finish (6/24)

Simplify for -1

Had an early 24 from randomly solving a 11+2 (and later discovered it was reducible to a 23):

L2 U2 R' F' // EO (4/4)
L // DR-44 2p (1/5)
(R2 U' R2 L2 D' L) // DR, 4a2 (6/11)
(U2 B2 [D' B2 U2 L2 U2 R2 F2 R2 D]) // HTR (11/22)
(L2 F2) // finish (2/24)

[] = (U F2 U2 L2 B2 R2 B2 U) // -1

(L' U2 D R) // EO (4/4)
R2 F2 U' B D' F' // DR, 4b2 2e (6/10)
(L2 U2 B2 U' R2 D') // HTR (6/16)
(R2 D2 R2 B2 R2) // Leave slice (5/21)

Slice in +1

Missed the 4c6e from this eo

(L') L' U2 R // EO (4/4)
(U') // DR-32 (1/5)
(R2 B' D B' D) // DR, 2c3 (5/10)
(F' U2 L2 F' R2 F) // HTR (6/16)
(L2 F2 D2 F2) // Leave slice (4/20)

Slice in +0

R' F' B' R // EO (4/4)
F2 U2 D' B // DR, 4c3 (4/8)
F2 U2 L2 D' F2 D2 L2 D' L2 D' // HTR (10/18)
F2 B2 U2 R2 // Leave slice (4/22)

Slice in +0

Optimal is 20 with 5qt

Bruh, found the 9+2 at like 50 minutes but I'm stupid to not check easy stuff.

(F2 L) B' D2 R' // EO (5/5)
F2 D2 F D' F U' // DR, 4b2 2e (6/11)
(U2 D2 L2 D2 F' R2 B') // HTR (7/18)
(U2 F2 U2 B2) // finish (4/22)

U' R' U' B // EO (4/4)
U // DR-44 (1/5)
R' B2 D2 L' U' // DR, 2c3 4e (5/10)
D2 R' (F2 R D2 R') // HTR (6/16)
(F2 L2 U2 B2 D2) // Leave slice (5/21)

Slice in +1

(U F' U) // EO (3/3)
(R) // DR-44 (1/4)
B R // DR, 2c5 (2/6)
D2 B' U2 F' (U2 F' D2 F' L2 F) // HTR (10/16)
(L2 D2 L2 U2) // Leave slice (4/20)

Slice in +0

B' (B U R F) // EO (5/5)
(U R L') // DR-32 (3/8)
(U2 L D' L) // DR, 2c3 2e (4/12)
U R2 B2 D' L2 B2 U' // HTR (7/19)
R L U2 B2 R L // finish (6-2/23)

Had a 11+3 that I misscounted as 10+3 and a fake 22 to slice but no +0/1

R B' R B L // EO (5/5)
(U2 B2 U L2 B') // DR, 4b2 4e (5/10)
D R2 D L2 U R2 U // HTR (7/17)
R2 U2 F2 B2 L2 D2 // finish (6/23)