If the only entries to the dummy are in the trump suit, you can’t put the cart before the horse; you have to use the trump entries to help you set up and use the side suit. Hence, drawing all your opponents’ trumps may have to wait.
The dangers of trumping a side suit increase when the opponents still have trumps. When you trump a card, the player who plays after you may also be void in that suit and may be able to play a higher trump card and take the trick, called overtrumping. Overtrumping can be a major pain in the you-know-where.
In addition, you may have entry problems. What if you set up a long suit and then can’t get back to the dummy to use it? Well, you may be hoping for some sympathy, but if you don’t have the entries, why bother trying to set up the suit? It can’t work!You also need enough trumps in your hand to trump a card or two in the suit you’re establishing and still have enough trumps left to remove all your opponents’ trump cards. Sometimes you’re not dealt such riches in the trump suit.
Don’t despair. You should know the downside to establishing a suit just so you’re aware that it doesn’t always work out. Nevertheless, with a strong trump suit, dummy entries, and losers in other suits, consider establishing a five- or six-card side suit even though it may be so puny that you can’t bear to look at it.