To better explain (and so I can 'consolidate' my thinking on this), here's examples from my current insane/insane game, just before I started my second city. Note, this isn't a 'bad start' as you're asking about, it's just an example of putting off a second city and building up the capital, to be able to defend against insane/insane. The strategy here may be useful in some 'bad start' games where you have a decent starting location but are 'boxed' in, helping you to break out. Against a very strong AI boxing you in at high difficulty levels I don't think this (or anything else, really) can help, as the AI at high difficulty levels researches/builds/etc. too fast.
It's currently season 72, I only have 1 city, and am ready to finally build city #2.
My capital, a 3/3/3 fortress (with scrying pool so 4 essence):

Note I have 2 unit-enhancing city spells, that's all I have at this time. I added more as I got them. I put these 2 unit-enhancing spells off until just before the units were created to get the most out of propaganda and inspiration (that I had been using), then exchanged them for the unit-enhancing spells.
I had a very nice second city location available, but it was judged too far to defend it and the capital at the time, especially as I didn't have economics (for its road between cities) at the time:

Here's a zoomed-out view, outpost to the south, capital in the middle, and second city site to the upper right:

Instead of founding a second city, I built this outpost south of my capital:

Gold mine, earth shard, clay pit. It was a bit of a chance, but deemed much less risky than the second city site, as the outpost is on a 'dead end' peninsula I had cleared so was fairly safe from wandering mobs and AI. The second city site has open, unexplored land to its east, north, and west -- too many unknowns.
Here's my 'finished' army, with which I felt I could finally sufficiently defend 2 cities:

Sov, lvl 3 warrior champ, Brothers Sparus (the quest guys), and 3 spear maidens. I had researched economics by this time so would have a road between the cities, so 1 good stack should be able to defend both cities (or so I hoped). I also could relatively quickly start/complete a second/third army to defend a third/subsequent cities.
I guess the Cliff's Notes version of all this is that sometimes slow is fast, and fast is slow -- Delay subsequent cities then break out fast, instead of making a number of cities that you can't defend against bad luck and wandering mobs/AI.