SS link question

[ketanco]

In construction industry it is often not wanted to put negative lags between activities such as

(Predecessor Activity) FS - x days

I can understand that, as this means we are depending our link on something in the future and has not happened yet so it is not recommended.



Instead, it is suggested to use

(Predecessor Activity) SS + y days

But even here we are talking about something in the future. Because we do not know how well the predecessor will progress during that y days, or will it progress according to plan, will it progress y days worth of work as planned, that would allow the start of successor after y days worth of work.

We take care of this problem by eliminating the lags alltogether, and instead, put a milestone for start, then put something like %40 of predecessor, then link it with a simple FS to successor, and then at the same time continue the remaining of predecessor. This would be the theoretically correct way right? But it looks like this complicates the schedule a great deal. What is the best way to deal with this?