« In October 2014 we started announcing a few longer-than-/24 prefixes and determined they were not very visible according to the Routing Information Service (RIS) and RIPE Atlas measurements.

[...]

Both control plane and data plane measurements show low (15-30%) visibility/reachability for longer-than-/24 prefixes out of ARIN's 23.128/10 address space. This makes longer-than-/24 prefixes not usable for the purpose of providing global Internet service, and if one requests address space from ARIN from this particular address block, requesting a /24 seems to be the wise choice.

Our efforts in September 2015 to try to maximise reachability of these prefixes had very little effect. Putting the setup behind AS3333 and asking our transits about this didn't change things much. Neither did making the longer-than-/24 prefixes visible at the Amsterdam Internet Exchange (AMS-IX) route servers. »

Via le twitter de Stéphane Bortzmeyer.