What I find hardest (as a manual installer) is those packages which were designed with a package manager in mind and end up depending on many third party packag

What I find hardest (as a manual installer) is those packages which were designed with a package manager in mind and end up depending on many third party packages rather than incorporating the needed functionality. As an example, program X might need to compute a statistic like the skewness of a distribution. A stats package might implement the skewness calculation, so the author of X adds the dependency and calls the right function. However, building the stats package might require a Fortran compiler and some matrix libraries, since the stats package does much more than compute skewness. Another approach would be for the author of X to incorporate the few tens of lines needed for the skewness as part of X. This is of course more work for the author X, so I can well understand the desire to simply declare it as a dependency.