At home, your dog knows the room and its distractions. At the park, smells, movement, and other dogs compete for attention. A cue learned in one place may need fresh practice in other places. This is a training gap you can work on, not a reason to punish your dog.
Change one thing at a time
Start in an easy room, then a quiet outdoor place, then a slightly busier one. Make the task shorter or closer when you change setting. Reward the behavior your dog can do there before adding distance or distractions. There is no magic number of locations or days that proves a cue is reliable.
Where should I start?
Choose what fits. Nothing is saved or submitted.
Keep recall safe
Use a suitable long line in a safe, permitted space while practicing recall. Do not test an untrained cue off-leash near traffic, wildlife, or other hazards. If your dog cannot respond, get closer or move to an easier place, and keep the next practice successful. For recall-specific steps, read the companion article.