The two rules are less than 4 hours each way and it must be doable by public transport, the point of hotspots are to provide information useful to travelers, like you mentioned it would be unwise to do this day-trip and therefore it would not convey any useful information
I would more call it guiding principles
than rules. But yeah, taking a 1 a.m. train to be back at 11 p.m. is not the intention.
Traveling back and forth for 12 hours to see a place for 2-3 hours is not something wise but it is possible to visit these places in a single day. Besides you can take the night bus departing at 1:00 am, reach Safranbolu at 6am, spend 12 hours there and take back the 6pm bus.
If we were to use your approach, Kopenhagen would be in the Hamburg hotspot and vice versa. My assumption would be morning (<4h) to, 4h onsite, afternoon (<4h) back.
I'm not sure if the southern levant (Eilat) Hotspot should exist as it literally states that St. Catherines area is no longer possible due to security reasons, along with that 3/4 require a major border crossing and are not possible by public transport
Yep. Borders are an issue with hotspots. See my comments re Suceava. Unless it's a green border, sites across real borders shouldnt be grouped into a hotspot. And public transport across hard borders tends to be limited.
Re Eilat: In peaceful times, I can see organized day trips having fast border transit. Peaseful no more.
Izmir is actually hotter than Istanbul.
To me, it sounds like a great itinerary that should be listed in the Turkey country topic. But not as a hotspot ;)
2) Edirne (lots of daily buses)
I have done the trip and that was already borderline. Traffic in Istanbul is hell and it took hours just to leave greater Istanbul. I spent more time each way on the bus than I had on site.
5) Troy (check www.flixbus.com
, possible as a day trip with bus. However, if you like to spend more time there, you should take night buses. There are minibuses from city center to Troy that lasts around an hour)
On the same trip I was eyeing Troy, but really couldn't make it work. And I made the Edirne thing work, so it's not that I shy away from a challenge.