There was a hand today which the majority of tables completed the transfer after interference despite holding only 2 cards in the suit, and they all landed a bad contract:
There were 5 tables today. 3 tables used weak NT and all of them started the bidding as above. 1 ended up at 4♠ and 2 ended up at 3♠. All got 8 tricks only.
One table using a strong notrump ended up at 1♣ - (/) - 1♠ - (2♥) - / - (/) - 2♠= which got the top, and my table, playing strong notrump also, had it overcalled by 3♦ which went -1.
If I used a weak notrump, in such case I would not complete the transfer after it was overcalled by 3♥, because I only had 2 cards in the suit.
What's your practice in handling Jacoby transfers if it is interfered?