The 1 km square recording on Raasay went through several overlapping stages:
During the final few years I used a combination of the last two methods. Maps were maintained for all taxa with 3 or more 1 km square records and so were lists of missing taxa for plants known in 20 or more recording units. These two together allowed rapid assessment of whether a plant was new to whichever recording unit I found myself in.
The use of lists of missing plants sensitises one to these species and may account in part for the high numbers of species that are recorded in 90+ recording units. See Numerical Analyses.