i just say OK. you know its gooig to be extra if u let it grow to high. its ok she will say.
i am not going to mow with the bag, higher than 6 inches, the bag gets nasty if is weeds im mowing, so i charge 10 or 15 extra just because i have to wash the mower after i mow her yard and i leave all the clippings or i should say nasty clumps of weeds, hey she does not have a lawn or grass she have a yard full of clover weeds and that is not my problem, or hers cause she rents, she just live 5 houses up in my street that's no drive. and i still charge like im driving if i mow over 6 inches i have to charge extra and will tell the customer to expect a brown lawn cause his lawn haven't been service at least for 3 weeks prior and if the grass gets to freaking high we are not talking about manicure lawn and that will obviously will not benefit the grass plant if u mow all the time like that all the time it can be done once in great while.
mowing lawns is easy, knowing the type of grass you mowing, and mowing in it in healthy ways, that's where you need to go the extra mile. on understanding the type of grass u are working with Kentucky, Fescues, ray grass Bermuda etc they all look green but each plant its different i don't know i know my southern grasses st. Agustin 3, or 3 1/2 inches Bermuda grass 1 to 2 inches when it gets hot 3 inches, zoysia grass 2 to 3 inches every grass is different and required different care.
just charge like u baging and when u fill not to bag then dont do it and if they ask you something i will say i can bag for you for an extra 5 bucks.