Walstib62, the article that you linked to is excellent, and helps counter the mistaken idea that shotgun microphones are simply "more directional" than, say, supercardioids, and/or that they can "reach" across greater distances. The way they actually work doesn't correspond to the visual assocations that people seem to make with them (telescopes, telephoto lenses, rifle barrels, rhinoceros penises or whatever).
Shotguns are basically designed to muffle any incoming sound that doesn't come from directly in front of them. They do this in a way that is highly frequency- and arrival-angle-specific. That can be helpful IF the unwanted, off-axis sound is distinctly different from whatever you're trying to record. Then there is low correlation between the sound processed by the interference tube and the sound that arrives on axis. The unwanted sound, arriving through the slots in the tube, is statistically unlikely to cause serious phase conflicts with the desired, on-axis sound. The desired sound must remain in front of the microphone in order for this to work, though; it may not also enter via the interference tube in any substantial amount.
The problem is that indoors, unless you record very close up and/or in an anechoic environment, the sound that reaches the capsule via the tube is ultimately the SAME sound that you're trying to record. To various degrees, it is reflected, delayed, diffused, and absorbed in an irregular, frequency- and angle-dependent manner before it reaches the microphone; then when that sound enters the interference tube, it undergoes further frequency- and angle-dependent cancellation effects. Finally, that greatly-munched-upon indirect sound, with various delays and rolloffs and peaks and valleys of up to 12 or 15 dB, gets combined with the direct sound at the microphone capsule.
The result is usually rather chaotic. Shotgun microphones used in indoor, reverberant spaces have highly irregular upper midrange and high-frequency response as a result of all these cancellation effects, and their overall integrated (all-angle or "diffuse-field") response is usually quite dull. If you try to use them to compensate for distant placement, you'll pick up mostly off-axis sound and relatively little direct, frontal sound, so the diffuse-field response is what will mainly determine the outcome of any such recording. And diffuse-field response is the Achilles' heel of shotguns as a class.
When professional recording engineers use shotgun microphones for stereo recording--which isn't all that often--the overall approach is M/S as a rule, and at fairly close range. There are good stereo shotgun microphones from Neumann, Audio-Technica, Sanken and Sennheiser which have a figure-8 microphone built in to the same housing as a (generally short) shotgun. Or a small figure-8 microphone for the "S" channel, such as a Schoeps CCM 8, can be clipped onto a single-channel shotgun microphone.
I mean, it's always a problem whenever your miking distance is greater than you want it to be. Sometimes, when your mike placement is constrained by other practical considerations, there is no really good solution. But a pair of good supercardioids will usually outperform any shotgun arrangement in that situation--even the best-sounding, multi-thousand-dollar shotguns from Schoeps, Neumann or Sanken--because the supercardioids' off-axis response is smoother, and combines with the on-axis pickup in a far less conflict-ridden manner.
--best regards