As you said pie charts are good for a limited number of slices. Once it gets too large to actually differentiate then you need some sort of bar or similar. But with few slices, a pie charts gives the best representation of division of the whole.
It seems to me that each has their use. I associate pie charts with portions of 100% of the picture such as spending in May 2023 by category or by payee. It focusus on proportion.
Bar charts, which I generally find more useful in making decisions, helps me understand trends over time. A bar chart of daily spending of top categories is probably more useful than 30 pie charts (one per day).
Broad picture, pie chart. Detailed picture, bar chart. Don’t get me started on donuts.
Pie Charts are generally a terrible way of conveying information, unless you’re highlighting a single category or datapoint as a percentage of a whole. It’s hard to see proportions unless they’re vastly different and are entirely useless when you’re interested in absolute values.
Pie charts are popular because they’re visually pleasing, but they’re less useful than other chart-types. You can’t really so things like Income Vs Expense with pie charts (even though some have tried…) for example. Bar charts aren’t idea for that either, something like a Sankey is far better than either.
I’ve been working in and around data visualization my entire career (so just a little over 25 years) and have seen some truly abhorrent use of Pie Charts, including trending. Yes… an entire row of Pie Charts with each representing some temporal data point. It looks pretty but is completely unreadable.
Pie charts are great for people who don’t like charts. They don’t say a whole lot. I can take percentages in a table and know what is being said. I don’t need a chart to tell that this slice is taking up a big part of the pie, but lots of people do need that visualization.
It depends what I am trying to graph. I use waterfalls and bar charts most often, but I also use line charts, histograms, area charts, tree maps, and combo bar/stacked bar+line charts. I rarely use pie charts.
Pie charts emphasize % proportions vs the whole. Bar charts show total $ amount for each category better, and $ amounts compared to other categories better. I don’t care about what % of the whole a category is. Just if I spent to much $ for a category. Plus I have a lot of categories.