Usually not as a weighted model. Get First, MQL and Latest touch clean and capture the rest as campaign membership — that answers most budget questions. Weighted multi-touch adds a modelling argument on top of data that is rarely clean enough to justify it.
The prerequisite for any multi-touch model is complete, consistently tagged touch data. Companies that jump to weighted models before fixing UTM discipline get a precise-looking number built on a source field that is 30% blank. Fix the entry points first; the model is the easy part.
Every claim above comes from work LeanScale published. These are the sources.