Hex values are taken from 0x0E and 0x18 in RAM after stepping on a tile in the day time
Grass:  0x0B = 11/256 (4.296875%)	No Encounter: 245/256		LUA Tested Rate:  447/10000  =  4.47%
Brush:  0x10 = 16/256 (6.25%)		No Encounter: 240/256		LUA Tested Rate:  611/10000  =  6.11%
Desert: 0x11 = 17/256 (6.640625%)	No Encounter: 239/256		LUA Tested Rate: 2926/42973  =  6.80%
Forest: 0x14 = 20/256 (7.8125%)		No Encounter: 236/256		LUA Tested Rate:  745/10000  =  7.45%
Swamp:  0x14 = 20/256 (7.8125%)		No Encounter: 236/256		LUA Tested Rate:  792/10000  =  7.92%
Hills:  0x1A = 26/256 (10.15625%)	No Encounter: 230/256		LUA Tested Rate: 1263/12322	 = 10.32%
Sea:    0x04 =  4/256 (1.5625%)		No Encounter: 252/256		LUA Tested Rate: 1601/100000 =  1.60%


G G
F G
G G

What are the odds of getting an encounter in three grass tiles versus one other tile?

No encounters in three grass tiles = 0.876553356647491455078125
Odds of one encounter = 12.345% (lol)
Never worth it, even for a hill tile.


What about two?  Three?  Four?

The following table was generated in Excel by:
 - filling one column (A) with:    =X/256
 - top of second column (B1) is:   =A1
 - top of second column (B2+) is:  =B1+(1-B1)*A2 (Drag down)
Can also use this to calculate walks for multiple tile types.  Leftmost column is the encounter chance of each tile.

															Odds of Encounter in (X) Steps							
Tile	Odds of Encounter (/256)	Odds of NO encounter	  1		  2		  3		  4		  5		  6		  7		  8
Grass	11							245						 4.3%	 8.4%	12.3%	16.1%	19.7%	23.2%	26.5%	29.6%
Brush	16							240						 6.3%	12.1%	17.6%	22.8%	27.6%	32.1%	36.3%	40.3%
Desert	17							239						 6.6%	12.8%	18.6%	24.0%	29.1%	33.8%	38.2%	42.3%
Forest	20							236						 7.8%	15.0%	21.7%	27.8%	33.4%	38.6%	43.4%	47.8%
Swamp	20							236						 7.8%	15.0%	21.7%	27.8%	33.4%	38.6%	43.4%	47.8%
Hills	26							230						10.2%	19.3%	27.5%	34.8%	41.5%	47.4%	52.7%	57.5%
Sea		4							252						 1.6%	 3.1%	 4.6%	 6.1%	 7.6%	 9.0%	10.4%	11.8%

It's worth it to take two extra steps in the grass to avoid...:
 - Five tiles of brush
 - Three tiles of forest or swamp
 - Two tiles of hills




Note that if you get an encounter right before walking around a high-encounter-chance tile, you should just take the shorter path.

	Suppose there are two forest tiles in your way, but you can alternatively step on two extra grass tiles to get around it (two forest tiles vs four grass tiles).  The rest of the path ahead and behind of the forest is more grass.
	
		Forest x2: 15.0%
		Grass x4: 16.1%
		So, you can spend 32 frames walking around to reduce your encounter chance.
	
	However, if you get an encounter right before the forest tiles...
		
		1/4 Forest + 2/4 Forest + 3/4 Grass = 8.82%
		1/4 Grass + 2/4 Grass + 3/4 Grass + Grass x2 = 14.2%
		The forest is both faster and a lower encounter chance.
	
	If you get an encounter two steps before the forest...
	
		1/4 Grass + 2/4 Forest + 3/4 Forest = 10.5%
		1/4 Grass + 2/4 Grass + 3/4 Grass + Grass x2 = 14.2%
		Forest is still better
	
	What about three steps before?
		1/4 Grass + 2/4 Grass + 3/4 Forest + Forest = 16.0%
		1/4 Grass + 2/4 Grass + 3/4 Grass + Grass x3 = 17.9%
		Forest is still better!