If you are paying for the service you better get your money's worth. Yes, you should ask for a convenient time and day for your landscape maintenance.
You should also ask for the best gardeners who know what they are doing, more often than not, maintenance companies send day laborers who have no clue what they are doing. This could harm your lawn and garden much more than you think.
Maintenance isn't just about pruning and keeping the plants in shape, make sure that all weeds are carefully removed, and the soil around plants is loosened up.
Also make sure that they provide the regular nutrition for your plants. You could even opt for organic manure for your landscape.
Ensure that all plants, bushes and trees are checked for pest, fungal infections and such and treated rightly.
It is your right to ask for all these things when you pay good money.