WHEN CONGRESS reformed its budget process in 1974, the problem was, in a way, that there were too many spending bills each year. Each committee and, in the case of appropriations, each subcommittee had its own footpath into the Treasury and back out again; there was no centralized process for setting spending targets and keeping score.

Now the pendulum has swung and the problem may be the opposite: too few bills. Particularly in the Reagan years, Congress has fallen into the pattern of mushing together and disposing of enormous amounts of business in just a few up-or-down votes on great legislative abstractions called budget resolutions, continuing resolutions and reconciliation bills. The prototype for these was the inventive Gramm-Latta bill of 1981, in which all the spending cuts of the president's first year were deftly rolled into one, in part to keep the Democrats and losing interest groups from picking them off one at a time. Now everyone has learned how to play. The rules are such that members have limited opportunity to take the omni-bills apart, to discriminate among their provisions. Are you for or against the future, yes or no? And hurry, please. That is the kind of question that is put to them.

The current reconciliation bill is a good example. The bill is an effort to make good on the fiscal 1986 budget resolution that Congress finally adopted before leaving town for its vacation in August. That resolution sets broad spending targets for the government as a whole and each of its 21 major functions -- expenditure categories such as national defense, agriculture, health, Social Security, veterans benefits, net interest payments. Most of these targets imply spending cuts, but the resolution does not spell out what these should be. It is left to each committee to make its share of the cuts in the programs in its jurisdiction. The work of the committees is then bundled into a reconciliation bill, and separately voted on.

The bill now taking shape is supposed to cut domestic spending by $68 billion over the next three years, meaning hold it that much below the levels it would otherwise reach under existing law. This in itself is a large enough legislative enterprise. It will take Congress into such subjects as the Medicare reimbursement rules under which a sixth of the national medical bill is paid each year; the farm price- and income-support structures; the eligibility rules for admission to veterans hospitals and the subsidies for Amtrak and postal service. Most of these were at least discussed during work on the budget resolution; they will not be surprises when they reach the floor.

But because the reconciliation bill is one of the few big trains that are likely to leave the station this year, members are also attaching other provisions. The banking committees are attaching the annual authorization bill for all the government's housing programs; those who want a bill passed this year say they see no other way. The House Ways and Means Committee has included a major change in the Aid to Families with Dependent Children program; states would have to offer the aid not just to families in which only one parent is present but also to those in which the principal wage earner is unemployed. The Senate Finance Committee has folded in a restructuring of the tobacco price-support program. The Finance bill also includes an important trade provision: it would impose a new tax on imports to extend and expand an expiring program of aid to workers who lose their jobs to competition from abroad. And of course there is more; there always is in an omni- bill.

We think Congress did the right thing in reforming the budget process 11 years ago. The system has not changed the spending instincts of the members; no system can. But it has provided a tote board for those instincts. It forces the members to make explicit fiscal choices and sign their names to the deficits they produce. But the big bills of the last few years are not a good way to legislate. There need to be limits imposed, and the bills should be divided to require separate votes on their major parts. The virtue of the budget process is that in many ways it has made members more accountable. The big bills as they are voted on now make them less so.