This is a selling agents intention to sell more so beware. You must have the largest block of land and of course a house to suit with all the bells and whistles.
Most have little concern as to how you will manage to meet the monthly mortgage payments. When you are dealing with agents make sure you have done your homework and be clear of mind with home and land requirements.
Pick a plan that suits you and find out what size lot will suit that particular home. Most builders will tell you the land size you would require for their home designs, just remember the sizes will usually be the minimum required.
If you are chasing a back yard make sure you make this perfectly clear when enquiring.