Guess there’s no harm in trying the packages, it might take off, it may also be a waste of time... only way to find out is try.
I PERSONALLY don’t think it will take off like you want, as someone mentioned you don’t really do one without the other (gutters / fascias) or I never have anyway. I think the discounted gutters is a better way of putting it though mate, for new window customers, it is sort of in the middle in terms of giving them something to think about without confusing what you do and your prices too much.
Anyway all the best whatever you decide, it’s your round and with this if you want to take 5 mins or 5 days Cleaning 1 house, you know what works for you to provide a quality job - although I would continue on the path of getting it down as you are 👍🏿 Keep it up