"actual time" in QUERY PLAN for parallel operation when loops is bigger than 1

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/14/using-explain.html
Description:

https://www.postgresql.org/docs/14/using-explain.html
The doc says
"the loops value reports the total number of executions of the node, and the
actual time and rows values shown are averages per-execution. This is done
to make the numbers comparable with the way that the cost estimates are
shown."

But I found for parallel operation, the above description maybe not
correct.

For example 
postgres=# create table c(id int);
CREATE TABLE
postgres=# insert into c select generate_series(1,1000000);
INSERT 0 1000000
postgres=# explain analyze select count(*) from c;
                                                             QUERY PLAN

-------------------------------------------------------------------------------------------------------------------------------------
 Finalize Aggregate  (cost=10633.55..10633.56 rows=1 width=8) (actual
time=290.460..290.508 rows=1 loops=1)
   ->  Gather  (cost=10633.33..10633.54 rows=2 width=8) (actual
time=289.605..290.484 rows=3 loops=1)
         Workers Planned: 2
         Workers Launched: 2
         ->  Partial Aggregate  (cost=9633.33..9633.34 rows=1 width=8)
(actual time=188.336..188.337 rows=1 loops=3)
               ->  Parallel Seq Scan on c  (cost=0.00..8591.67 rows=416667
width=0) (actual time=0.030..140.036 rows=333333 loops=3)
 Planning Time: 0.331 ms
 Execution Time: 290.607 ms
(8 rows)

postgres=# 

According to PG-doc, the "Parallel Seq Scan" node cost 140.036*3=420ms, but
the total cost for this SQL is only 290ms.
Is the output of this explain correct?