Often, when you have several cohorts, or rounds of capex, or multiple projects with different start dates, you end up with a “triangle” block in your model. This has one row for each cohort/ round of capex/ etc. and the costs start at different times for each row.
Openbox can create this for you. The attached file shows a simple example where you have a number of assets that are in service at different times. Deprecation starts at the given time for each one. Try playing around with changing the asset life for each project, and see how the results in the Openbox preview window change.
Looks like I cannot access the attachment