You cannot be prepared for every single potential delay...
The main issue for Smiler was the groundwork, where they thought they had a certain soil type, turned out they didn't, hence the numerous concrete retaining walls we've been given... Since the groundwork is the longest part of ride construction, and the type of issue involved has resulted in this...
Unfortunately this has been a result as well of Merlin's shorter construction time frames for rides, whereas before we would've had a couple of years preparation, this has been done in the space of about a year and a half...
I doubt they will go for a later opening thing on all rides, as Towers has been dead due to Smiler's delay... Would not be viable business wise to keep doing that...