Counting numbered posts with formula

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I am currently looking for a way to count posts.
I have 1- 50 posts so in total 50 posts.

If i split the posts in to work groups like the table below I can see if I have any overlap and subtract the number of posts work on twice to get back to my 50 total.

Book1 - 31-11-22.xlsx
	A	B	C	D	E
1	On/OFF	Start	End	Total	Overlap
2	1	1	10	10	2
3	1	9	20	12	0
4	1	21	30	10	0
5	1	31	40	10	0
6	1	41	50	10	0
7			TOTAL	52	2
8			Total - overlap	50
Sheet1

Cell Formulas
Range	Formula
E2:E6	E2	=IF(A2:A6=1,IF((B3:B7<=C2:C6)*(B3:B7>1),(C2:C6-B3:B7)+1,"0"),"OFF")
D2	D2	=IF(A2=1,(C2-B2)+1,"")
D3:D6	D3	=IF(A3:A6=1,IF((B3:B6>=B2:B5),IF((C3:C6>C2:C5),(C3:C6-B3:B6)+1,(C3:C6-B3:B6)+1),IF(B3:B6<=B2:B5,IF(C3:C6>C2:C5,(C3:C6-C2:C5)+E2:E5,FALSE))),"OFF")
E7	E7	=SUM(E2,E3,E4,E5,E6)
D7	D7	=SUM(D2,D3,D4,D5,D6)-G4-G3-G5-G6
D8	D8	=SUM(D7)-E7
Dynamic array formulas.

Even if I skip a couple of posts like below, in work group 2 I end on post 20 then work group 3 starts on 23, posts 21 and 22 havnt been works so I would like these deducted from the total, which again my spreadsheet performs great!

Book1 - 31-11-22.xlsx
	A	B	C	D	E
1	On/OFF	Start	End	Total	Overlap
2	1	1	10	10	2
3	1	9	20	12	0
4	1	23	30	8	0
5	1	31	40	10	0
6	1	41	50	10	0
7			TOTAL	48	2
8			Total - overlap	46
Sheet1

Cell Formulas
Range	Formula
E2:E6	E2	=IF(A2:A6=1,IF((B3:B7<=C2:C6)*(B3:B7>1),(C2:C6-B3:B7)+1,"0"),"OFF")
D2	D2	=IF(A2=1,(C2-B2)+1,"")
D3:D6	D3	=IF(A3:A6=1,IF((B3:B6>=B2:B5),IF((C3:C6>C2:C5),(C3:C6-B3:B6)+1,(C3:C6-B3:B6)+1),IF(B3:B6<=B2:B5,IF(C3:C6>C2:C5,(C3:C6-C2:C5)+E2:E5,FALSE))),"OFF")
E7	E7	=SUM(E2,E3,E4,E5,E6)
D7	D7	=SUM(D2,D3,D4,D5,D6)-G4-G3-G5-G6
D8	D8	=SUM(D7)-E7
Dynamic array formulas.

Now my issue starts if I overlap more groups.
Below I have group 2 starting at post 9 and finishing on 20.
Then group 4 also starting on post 9 and ending on 40.

In this case I can see clearly that posts 1 - 50 have had work done but my table stops correctly removing the duplicate work posts and is giveing me a total of 72 instead ofthe desired 50.

Book1 - 31-11-22.xlsx
	A	B	C	D	E
1	On/OFF	Start	End	Total	Overlap
2	1	1	10	10	2
3	1	9	20	12	0
4	1	21	30	10	22
5	1	9	40	32	0
6	1	41	50	10	0
7			TOTAL	96	24
8			Total - overlap	72
Sheet1

Cell Formulas
Range	Formula
E2:E6	E2	=IF(A2:A6=1,IF((B3:B7<=C2:C6)*(B3:B7>1),(C2:C6-B3:B7)+1,"0"),"OFF")
D2	D2	=IF(A2=1,(C2-B2)+1,"")
D3:D6	D3	=IF(A3:A6=1,IF((B3:B6>=B2:B5),IF((C3:C6>C2:C5),(C3:C6-B3:B6)+1,(C3:C6-B3:B6)+1),IF(B3:B6<=B2:B5,IF(C3:C6>C2:C5,(C3:C6-C2:C5)+E2:E5,FALSE))),"OFF")
E7	E7	=SUM(E2,E3,E4,E5,E6)
D7	D7	=SUM(D2,D3,D4,D5,D6)-G4-G3-G5-G6
D8	D8	=SUM(D7)-E7
Dynamic array formulas.

Does anyone have some fresh eyes to see what I am doing wrong?