size of indexes and tables (more than 1GB)

I read and have seen that when a table has more than 1GB it is divided
in several files with the names of inode,inode.1,inode.2,inode.3, etc.

I have a table of 1.3 GB (9.618.118 rows,13 fields) it is divided in
that way as i see on /PGDATA/base but each file has the same size i
mean
table inode (1.3GB), inode.1(1.3GB),inode.2(1.3GB) so is this not a
waste of space?, are those file sizes reusable by postgresql?.

The size of the table is 3 times bigger than, for instance Visual Fox
Pro dbf's? since is there fisically three times.

I am a little confuse on this.

I apreciatte anybody could explain this to me

Thanks in advance.