[baabaa]

For people playing transfers after 1♣, is it common to play that this system is on after:

1♣ - (dbl) ?

[nullve]

If you by "this system" just mean "transfers after 1♣", then the answer is Yes.

But some try to make use of the extra bidding space by assigning a meaning to XX (like "10+" or "4+ D") and adjusting the remaining structure, but then they're obviously not playing "system on" in the sense of bidding just like after 1♣-(P).

[helene_t]

Yes, system on is common.

I wonder if the difference between pass and redouble should be about the number of clubs. Maybe something like:
rdbl=0-2 clubs (but usually not 0 since we play wjs)
pass=3-4 clubs

Of course, most hands will bid something regardless of the number of clubs, but with some 0-4 points and no 6-card suit it is maybe nice to be able to help partner to decide what to do if next hand converts the double. Also, if opener has five clubs, it is good to know if it's safe to compete over next hand's bid.

You could also play 2-under transfers, i.e. rdbl=hearts etc. But then you aren't playing system on anymore so then it becomes more complicated.

[mikeh]

In both of my T-Walsh partnerships, we take advantage of the double by starting transfers with redouble. This avoids the main area of weakness of T-Walsh, which is the 1S response after 1C (P), which we play as 5-8 balanced (no major) or ‘any hand with diamonds as our longest suit’.

We use 1C (x) 1S as a good 2C bid, 1N as 9-11, and 2C as a weaker 2C bid. This is in the context of 14-16 1N, and opening virtually all flat 11 counts.

The odds of catching them at the one level, after opening 1C, are (in our view) not sufficient to use redouble as an offer to penalize.

[fromageGB]

I would say it is common, as it is the simplest option. Double is a free bid which my partnerships use to to transfer to diamonds on 5+ cards (and no 4 card major). Rebid or not depending on strength.

Without this ability we show diamonds by starting 1♠ (denying a major) and over a 1NT opener rebid we bid 2♦ to play or 2♠ (the major corresponding to the minor) as invitational, or a forcing 3♦ as game or slam seeking. The double allows the ability to show diamonds while rebidding 1NT if opponents allow, or to get the diamond bid in before opponents up the ante, which might destroy the invitational option otherwise.

[perko90]

I've been playing Transfer Walsh since shortly after ACBL made them legal (2018).
What's worked for us is to play system on over X and 1♦ interference.