Calculated time of predecessor and successor task

Hi

In standard system calculated time of predecessor and successor task are not strictly continued. For example, Task1 under Phase One is a predecessor task of Task3 which is under Phase Three, and Phase Two is between Phase One and Three. The earliest finish time of Task1 is 8.31, but the successor task Task3 does not begins on 9.1(maybe it's earliest start time is 10.1 e.g). That is because the system takes the duration of Phase Two into account. How to break this time structure and let Task3 starts strictly following Task1(here the earliest start date is 9.1). Is there any configuration or BAPI we can use here?

Regards,

Yemi