Just to confirm @Jaap Scherphuis's comment that non-rectangular arrangements may be competitive here are some requiring 33 strokes, one fewer than the best rectangular ones according to Jaap.
For the sake of clarity: By rectangular we mean solid rectangular, no holes, no chamfered corners, etc. So the below are not rectangular because they have holes.
This is the complete set (up to symmetry) of optimal arrangements constrained to a 9x7 bounding box determined by exhaustive brute force computer search.
There also are multiple 33s in an 8x8 bounding box, for example: