Tell a director Tech is Tech, and blocking is done? No major changes to blocking a week before tech?
Seriously, how realestic is that? I mean, if a director wants to change blocking during tech, it's still his show, it's still his rehearsal - what is the point of lighting or teching anything if the director wants to make changes, especially since if he doesn't do it during tech, he is going to do it during previews - and then you have to retech.
I guess at the level I work with, my job in tech is to make sure I can finish teching the show . . . as long as I have time for that, the director can do anything he wants.
Wants a show gets on stage, in costume, in front of the set, etc, etc - you will find that things have to change and things will need to change - holding a director to some sort of artifical deadline is silly, and most likely not in the best interest of the show. BUT, the director may need to know that due his changes, things may fall beind or need to wait (new blocking, new special, new hanging position, etc, etc.).
Hopefully all changes are done to improve the show, and everyone wants to make the show the best.
The concept of "NO CHANGE" dates does not utimately serve the show, but any professional director worth a crap will know that last minute changes will not always be able to be implemented, but it's my job to help see how they can. A good lighting designer should be able to have a plot that will accomodate changes, or allow additions. (At my current theatre, a major regional theatre, the light plot is due BEFORE we even finish staging the show . . . and often hung by the time the deisgner sees a run . . . so they need to be proactive in their design, anticipating changes.) It's my job to communicate blocking issues that may not work with their plot.
I do think young Stage Managers should enter the world thinking a show is ever set until open. (For example on my current show, we reblocked an entire dance after the third preview, cutting out 2 characters . . . it happens - it happens all the time.)