Large jobs?? The increase of the size = increase the headaches.
Calibrating your own resources with other trades, the owner, the architect, the site foreman, wholesalers, transport for the lads..... The list goes on trust me. I would rather have 4 house re-wires in the same time and take a little bit less in money.
The big jobs will come in time via your reputation. But never bite off more than you can chew (EM lights/fire alarm). If/when that happens, subby it out to another firm/company that can do the job. It works out in the long run, trust me on that.
The next job after this is an old bank vault that needs ripping out and getting back to an industrial premise. 12 weeks due to the difficulties of works. Now that is interesting!!! 75% rip out,25% install with loads of cherry picker work outside in winter, looking forward to doing that myself lol.
At the same time as this I will be wire-ring up another site which is a 8-10 apartment block new build. I may be taking a bit of time away from the forum at this stage in my life. Needs a lot of attention, so I will take a bit of a break.
The big jobs will come. It is how you run them that counts when you building yourself up. Can you stand a £2k mistake? It is your pocket, your income and if you make a mistake can you take the hit? Been there and done that. Some of the other members on here have been hit for ssssooo much more. £2k is childs play but it still hurts when your starting out.