¿Algo así?
SQL> with test (name, day, srvc_inv) as
2 (select 'bill', 1, 1 from dual union all
3 select 'bill', 2, 1 from dual union all
4 select 'bill', 3, 0 from dual union all
5 select 'bill', 4, 0 from dual union all
6 select 'bill', 5, 1 from dual union all
7 select 'bill', 6, 0 from dual union all
8 select 'susy', 1, 1 from dual union all
9 select 'susy', 2, 0 from dual union all
10 select 'susy', 3, 1 from dual union all
11 select 'susy', 4, 0 from dual union all
12 select 'susy', 5, 1 from dual
13 ),
14 inter as
15 (select name, day, srvc_inv,
16 nvl(lead(srvc_inv) over (partition by name order by day), 0) lsrvc
17 from test
18 )
19 select name,
20 sum(case when srvc_inv <> lsrvc and lsrvc = 0 then 1
21 else 0
22 end) grp
23 from inter
24 group by name;
NAME GRP
---- ----------
bill 2
susy 3
SQL>
