Both sides can snap, the right and left and of course there is the upper edge or the lower edge. At a division of one mm I think it will be hard to determine which edge is snapping and to which point.
At a 30 pixel snap it is hard to know what grid point one of the edges is snapping to.
When I have snapping on, which is rarely, I have set
- Resolution to 10.00 mm
- Subdivision to 1
- Snap range to 5 pixels
Generally, when working I don’t worry too much about exact placement on the page because I usually copy to Writer or export to svg or png. I do like to have good or exact placement of objects relative to each other.
- I have Helplines visible, View > Grid & Helplines > Helplines while moving. If I can line up a helpline with a point on another object, that is often sufficient.
- I do use the Position & Size (Format > Position & Size F4) dialogue to position and size objects exactly. Sometimes a spreadsheet is handy to do the calculations and store positions for future calculations
- I use the Align icon frequently for both exact and sufficient positioning
- At zoom 180% and 1:1 the arrow keys move an object 1 mm. Alt+Arrow moves it 0.15 mm. Shift+Arrow moves an object 10 mm