That is a standard insert install.

If you want to, have him cut holes in the weight boxes and either blow in some insulation or some foam.

You have to usually ask for that type of stuff. We do it as a default but talk about it when in the home.

Thanks for the prompt response. So, assuming I don't care about the extra insulation, is his proposed install (what you call the "standard insert install") the best possible install of inserts for fit/longevity?

Thanks again.

Thanks for the prompt response. So, assuming I don't care about the extra insulation, is his proposed install (what you call the "standard insert install") the best possible install of inserts for fit/longevity?

Thanks again.

Not sure about best but probably pretty industry standard.

You usually smack the pulley so they are flush, pull the blind stop, push the window in, spray foam around it, and cap the exterior.

If its historic, you might pull the interior stop, drop the window up against the blind stop, replace the interior stop, and trim out the exterior.

If there are weight pocket covers I pull the weights and put fiberglass insulation in through it. If there is no cover I do not add. Around here I would say 9 out of 10 windows that have weights have weight covers. I prefer to pry or unscrew the pulley as pounding it in can crack the frame. The pressed in pulleys can be stubborn and sometime will be pounded in. If I was doing my own house I would either remove casing or inject foam if there was no easy access.

+1 to Todd's feedback.

You won't have another opportunity to as easily insulate this void space again.

Talk to your installer and see if they can't accommodate that request.