If the target cannot be destroyed by stand-off weaponry, blown up by spec-ops or long-range artillery and the target constitutes a high-risk target that needs to be taken out, will an air strike be planned.
As Kengou stated, the planning phase takes a lot of time, air defenses, routes, waypoints, refueling, C2 elements, target recon, area recon and god knows what else needs to be included, including risk to the strike package itself of course and planning for losses, CSAR and so on.
After that, it basically comes down to follow the plan, improvise, adapt and overcome whatever may be thrown at the strike package and work towards a successful mission.
It's never "simple" or "easy", ask any DCS veteran mission designer out there. There is a lot of stuff going on behind the curtain we never see or experience.