No, we don’t need to compute e very often; it’s value is pretty well known. The article is just showing off Raku (or Perl 6 as it was then known) by writing a small program of moderate complexity that still manages to show off some of Raku’s interesting features. Computing approximations of e is merely an interesting exercise; it’s not the point.

The question that justinator asked was what good uses Raku’s indefinite series have. This article points out that different ways of approximating e grow at different rates, so it is appropriate to associate a different range of trial values with each of those methods. Dörrie's bounds uses powers of 10 as shown. Others use powers of 2. Newton’s method uses sequential trial values, since it grows really fast:

    #| Newton's series
    assess -> \k=0..∞ { sum (0..k)»!»⁻¹ }

And several methods compute approximations in a single step, so they don’t take a trial value at all:

    #| Castellano's coincidence
    assess { (π⁴ + π⁵) ** ⅙ }

    #| Sabey's digits
    assess { (1+2**(-3×(4+5)))**(.6×.7+8⁹) }

    #| Piskorowski's eight 9s
    assess { (9/9 + 9**-9**9) ** 9**9**9 }

These are a lot of fun, but of course they can also be profound:

    #| From Euler's Identity
    assess { (-1+0i) ** (π×i)⁻¹ }

For those who are interested, the article shows off a lot of obvious syntactic features like superscripts and hyperoperators, but there are also things like classes and roles and new operators as well. It really is a nice tour.

You’re welcome.