So after more thought, the roll off has not progressed further, but SkySafari did clarify my thoughts/ understanding a bit more.
Essentially declination is a good perspective on assessing suitability for an observatory, when horizons are going to be a compromise at your potential locations.
Essential my spot has access to -90 to +30 (just) but with significant compromise East and west. So at some point of the year I should be able to observe anything within these declinations when they clear my east west horizons... its simple and obvious really. Doh!
